diff --git a/icu4c/source/common/locid.cpp b/icu4c/source/common/locid.cpp
index e87b8b3972a..e6a93eaf1c4 100644
--- a/icu4c/source/common/locid.cpp
+++ b/icu4c/source/common/locid.cpp
@@ -1090,7 +1090,7 @@ Locale::getBaseName() const
         // the computation of variantBegin leaves it equal to the length
         // of fullName if there is no variant.  It should instead be
         // the length of the baseName.  Patch around this for now.
-        if (variantBegin == uprv_strlen(fullName)) {
+        if (variantBegin == (int32_t)uprv_strlen(fullName)) {
           ((Locale*)this)->variantBegin = baseNameSize;
         }
     }
diff --git a/icu4c/source/common/normalizer2impl.cpp b/icu4c/source/common/normalizer2impl.cpp
index 48ceb12cb02..c6d0c6151e3 100644
--- a/icu4c/source/common/normalizer2impl.cpp
+++ b/icu4c/source/common/normalizer2impl.cpp
@@ -249,7 +249,7 @@ Normalizer2Impl::~Normalizer2Impl() {
 
 UBool U_CALLCONV
 Normalizer2Impl::isAcceptable(void *context,
-                              const char *type, const char *name,
+                              const char * /* type */, const char * /*name*/,
                               const UDataInfo *pInfo) {
     if(
         pInfo->size>=20 &&
@@ -336,7 +336,7 @@ enumPropertyStartsRange(const void *context, UChar32 start, UChar32 /*end*/, uin
 U_CDECL_END
 
 void
-Normalizer2Impl::addPropertyStarts(const USetAdder *sa, UErrorCode &errorCode) const {
+Normalizer2Impl::addPropertyStarts(const USetAdder *sa, UErrorCode & /*errorCode*/) const {
     /* add the start code point of each same-value range of each trie */
     utrie2_enum(normTrie, NULL, enumPropertyStartsRange, sa);
 
@@ -1356,7 +1356,7 @@ enumRangeHandler(const void *context, UChar32 start, UChar32 end, uint32_t value
 // Collect (OR together) the FCD values for a range of supplementary characters,
 // for their lead surrogate code unit.
 static UBool U_CALLCONV
-enumRangeOrValue(const void *context, UChar32 start, UChar32 end, uint32_t value) {
+enumRangeOrValue(const void *context, UChar32 /*start*/, UChar32 /*end*/, uint32_t value) {
     *((uint32_t *)context)|=value;
     return TRUE;
 }
@@ -1678,7 +1678,7 @@ unorm2_swap(const UDataSwapper *ds,
 
     if(length>=0) {
         length-=headerSize;
-        if(length<sizeof(indexes)) {
+        if(length<(int32_t)sizeof(indexes)) {
             udata_printError(ds, "unorm2_swap(): too few bytes (%d after header) for Normalizer2 data\n",
                              length);
             *pErrorCode=U_INDEX_OUTOFBOUNDS_ERROR;
diff --git a/icu4c/source/common/resbund.cpp b/icu4c/source/common/resbund.cpp
index 082c5ab01f4..e1a58d2dc7e 100644
--- a/icu4c/source/common/resbund.cpp
+++ b/icu4c/source/common/resbund.cpp
@@ -1,6 +1,6 @@
 /*
 **********************************************************************
-*   Copyright (C) 1997-2008, International Business Machines
+*   Copyright (C) 1997-2010, International Business Machines
 *   Corporation and others.  All Rights Reserved.
 **********************************************************************
 *
@@ -360,7 +360,7 @@ UnicodeString ResourceBundle::getStringEx(const char* key, UErrorCode& status) c
 const char*
 ResourceBundle::getVersionNumber()  const
 {
-    return ures_getVersionNumber(fResource);
+    return ures_getVersionNumberInternal(fResource);
 }
 
 void ResourceBundle::getVersion(UVersionInfo versionInfo) const {
@@ -373,7 +373,7 @@ const Locale &ResourceBundle::getLocale(void) const
     UMTX_CHECK(NULL, (fLocale == NULL), needInit);
     if(needInit) {
         UErrorCode status = U_ZERO_ERROR;
-        const char *localeName = ures_getLocale(fResource, &status);
+        const char *localeName = ures_getLocaleInternal(fResource, &status);
         Locale  *tLocale = new Locale(localeName);
         // Null pointer check
         if (tLocale == NULL) {
diff --git a/icu4c/source/common/uchar.c b/icu4c/source/common/uchar.c
index d9f5f12e63d..120e0688fd3 100644
--- a/icu4c/source/common/uchar.c
+++ b/icu4c/source/common/uchar.c
@@ -29,6 +29,7 @@
 #include "utrie2.h"
 #include "udataswp.h"
 #include "uprops.h"
+#include "ustr_imp.h"
 
 #define LENGTHOF(array) (int32_t)(sizeof(array)/sizeof((array)[0]))
 
diff --git a/icu4c/source/common/ucnv_lmb.c b/icu4c/source/common/ucnv_lmb.c
index 9d6cffd2eb8..275e7d52679 100644
--- a/icu4c/source/common/ucnv_lmb.c
+++ b/icu4c/source/common/ucnv_lmb.c
@@ -1,6 +1,6 @@
 /*  
 **********************************************************************
-*   Copyright (C) 2000-2009, International Business Machines
+*   Copyright (C) 2000-2010, International Business Machines
 *   Corporation and others.  All Rights Reserved.
 **********************************************************************
 *   file name:  ucnv_lmb.cpp
@@ -952,7 +952,7 @@ _LMBCSFromUnicode(UConverterFromUnicodeArgs*     args,
             uprv_memset(groups_tried, 0, sizeof(groups_tried));
 
             /* check for non-default optimization group (Strategy 3A )*/
-            if (extraInfo->OptGroup != 1 && ULMBCS_AMBIGUOUS_MATCH(group, extraInfo->OptGroup))
+            if ((extraInfo->OptGroup != 1) && (ULMBCS_AMBIGUOUS_MATCH(group, extraInfo->OptGroup)))
             {
                 /*zhujin: upgrade, merge #39299 here (Lotus) */
                 /*To make R5 compatible translation, look for exceptional group first for non-DBCS*/
diff --git a/icu4c/source/common/ucnv_u16.c b/icu4c/source/common/ucnv_u16.c
index 927f9247438..a2044aa0ed6 100644
--- a/icu4c/source/common/ucnv_u16.c
+++ b/icu4c/source/common/ucnv_u16.c
@@ -1293,7 +1293,7 @@ _UTF16Open(UConverter *cnv,
              * (See ucnv_createConverterFromSharedData() in ucnv_bld.c.)
              * UTF-16,version=2 fromUnicode() always writes a big-endian byte stream.
              */
-            cnv->sharedData=&_UTF16v2Data;
+            cnv->sharedData=(UConverterSharedData*)&_UTF16v2Data;
             uprv_memcpy(cnv->subChars, _UTF16v2Data.staticData->subChar, UCNV_MAX_SUBCHAR_LEN);
         }
         _UTF16Reset(cnv, UCNV_RESET_BOTH);
diff --git a/icu4c/source/common/ucnvmbcs.c b/icu4c/source/common/ucnvmbcs.c
index cf269adf9da..f473f005ee9 100644
--- a/icu4c/source/common/ucnvmbcs.c
+++ b/icu4c/source/common/ucnvmbcs.c
@@ -3939,7 +3939,7 @@ ucnv_MBCSFromUnicodeWithOffsets(UConverterFromUnicodeArgs *pArgs,
     uint32_t asciiRoundtrips;
     uint32_t value;
     uint8_t si_value[2], so_value[2], si_value_length, so_value_length;
-    int32_t length, prevLength;
+    int32_t length = 0, prevLength;
     uint8_t unicodeMask;
 
     cnv=pArgs->converter;
diff --git a/icu4c/source/common/ucol_swp.cpp b/icu4c/source/common/ucol_swp.cpp
index ede8dd68a82..dce23cbd77b 100644
--- a/icu4c/source/common/ucol_swp.cpp
+++ b/icu4c/source/common/ucol_swp.cpp
@@ -47,7 +47,7 @@ utrie_swap(const UDataSwapper *ds,
     }
 
     /* setup and swapping */
-    if(length>=0 && length<sizeof(UTrieHeader)) {
+    if(length>=0 && (uint32_t)length<sizeof(UTrieHeader)) {
         *pErrorCode=U_INDEX_OUTOFBOUNDS_ERROR;
         return 0;
     }
@@ -108,7 +108,7 @@ ucol_looksLikeCollationBinary(const UDataSwapper *ds,
                               const void *inData, int32_t length) {
     const uint8_t *inBytes;
     const UCATableHeader *inHeader;
-    UCATableHeader header={ 0 };
+    UCATableHeader header={ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, {0,0,0,0}, {0,0,0,0}, {0,0,0,0}, {0,0,0,0}, 0 };
 
     if(ds==NULL || inData==NULL || length<-1) {
         return FALSE;
@@ -155,7 +155,7 @@ ucol_swapBinary(const UDataSwapper *ds,
 
     const UCATableHeader *inHeader;
     UCATableHeader *outHeader;
-    UCATableHeader header={ 0 };
+    UCATableHeader header={ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, {0,0,0,0}, {0,0,0,0}, {0,0,0,0}, {0,0,0,0}, 0 };
 
     uint32_t count;
 
@@ -363,7 +363,7 @@ ucol_swapInverseUCA(const UDataSwapper *ds,
 
     const InverseUCATableHeader *inHeader;
     InverseUCATableHeader *outHeader;
-    InverseUCATableHeader header={ 0 };
+    InverseUCATableHeader header={ 0,0,0,0,0,{0,0,0,0},{0,0,0,0,0,0,0,0} };
 
     /* udata_swapDataHeader checks the arguments */
     headerSize=udata_swapDataHeader(ds, inData, length, outData, pErrorCode);
diff --git a/icu4c/source/common/unorm.cpp b/icu4c/source/common/unorm.cpp
index a5c5ebdc528..15f7808e453 100644
--- a/icu4c/source/common/unorm.cpp
+++ b/icu4c/source/common/unorm.cpp
@@ -92,19 +92,19 @@ static UVersionInfo dataVersion={ 0, 0, 0, 0 };
 
 U_CDECL_BEGIN
 
+#if !UNORM_HARDCODE_DATA
 static UBool U_CALLCONV
 unorm_cleanup(void) {
-#if !UNORM_HARDCODE_DATA
     if(normData!=NULL) {
         udata_close(normData);
         normData=NULL;
     }
     dataErrorCode=U_ZERO_ERROR;
     haveNormData=0;
-#endif
 
     return TRUE;
 }
+#endif
 
 #if !UNORM_HARDCODE_DATA
 
diff --git a/icu4c/source/common/uprops.cpp b/icu4c/source/common/uprops.cpp
index 37409cec9cc..87dff030852 100644
--- a/icu4c/source/common/uprops.cpp
+++ b/icu4c/source/common/uprops.cpp
@@ -444,7 +444,7 @@ u_getIntPropertyValue(UChar32 c, UProperty which) {
 }
 
 U_CAPI int32_t U_EXPORT2
-u_getIntPropertyMinValue(UProperty which) {
+u_getIntPropertyMinValue(UProperty /*which*/) {
     return 0; /* all binary/enum/int properties have a minimum value of 0 */
 }
 
diff --git a/icu4c/source/common/uresbund.c b/icu4c/source/common/uresbund.c
index 9901e1417fe..10654e477e7 100644
--- a/icu4c/source/common/uresbund.c
+++ b/icu4c/source/common/uresbund.c
@@ -1905,8 +1905,8 @@ ures_getUTF8StringByKey(const UResourceBundle *resB,
  *  INTERNAL: Get the name of the first real locale (not placeholder) 
  *  that has resource bundle data.
  */
-U_CAPI const char*  U_EXPORT2
-ures_getLocale(const UResourceBundle* resourceBundle, UErrorCode* status)
+U_INTERNAL const char*  U_EXPORT2
+ures_getLocaleInternal(const UResourceBundle* resourceBundle, UErrorCode* status)
 {
     if (status==NULL || U_FAILURE(*status)) {
         return NULL;
@@ -1919,6 +1919,14 @@ ures_getLocale(const UResourceBundle* resourceBundle, UErrorCode* status)
     }
 }
 
+U_CAPI const char* U_EXPORT2 
+ures_getLocale(const UResourceBundle* resourceBundle, 
+               UErrorCode* status)
+{
+  return ures_getLocaleInternal(resourceBundle, status);
+}
+
+
 U_CAPI const char* U_EXPORT2 
 ures_getLocaleByType(const UResourceBundle* resourceBundle, 
                      ULocDataLocaleType type, 
@@ -2154,8 +2162,18 @@ ures_countArrayItems(const UResourceBundle* resourceBundle,
     }
 }
 
-U_CAPI const char*  U_EXPORT2
-ures_getVersionNumber(const UResourceBundle*   resourceBundle)
+/**
+ * Internal function.
+ * Return the version number associated with this ResourceBundle as a string.
+ *
+ * @param resourceBundle The resource bundle for which the version is checked.
+ * @return  A version number string as specified in the resource bundle or its parent.
+ *          The caller does not own this string.
+ * @see ures_getVersion
+ * @internal
+ */
+U_INTERNAL const char* U_EXPORT2 
+ures_getVersionNumberInternal(const UResourceBundle *resourceBundle)
 {
     if (!resourceBundle) return NULL;
 
@@ -2198,10 +2216,16 @@ ures_getVersionNumber(const UResourceBundle*   resourceBundle)
     return resourceBundle->fVersion;
 }
 
+U_CAPI const char*  U_EXPORT2
+ures_getVersionNumber(const UResourceBundle*   resourceBundle)
+{
+    return ures_getVersionNumberInternal(resourceBundle);
+}
+
 U_CAPI void U_EXPORT2 ures_getVersion(const UResourceBundle* resB, UVersionInfo versionInfo) {
     if (!resB) return;
 
-    u_versionFromString(versionInfo, ures_getVersionNumber(resB));
+    u_versionFromString(versionInfo, ures_getVersionNumberInternal(resB));
 }
 
 /** Tree support functions *******************************/
diff --git a/icu4c/source/common/uresimp.h b/icu4c/source/common/uresimp.h
index f811781b8aa..fdae4868c14 100644
--- a/icu4c/source/common/uresimp.h
+++ b/icu4c/source/common/uresimp.h
@@ -242,4 +242,33 @@ ures_getVersionByKey(const UResourceBundle *resB,
                      UErrorCode *status);
 
 
+/**
+ * Internal function.
+ * Return the version number associated with this ResourceBundle as a string.
+ *
+ * @param resourceBundle The resource bundle for which the version is checked.
+ * @return  A version number string as specified in the resource bundle or its parent.
+ *          The caller does not own this string.
+ * @see ures_getVersion
+ * @internal
+ */
+U_INTERNAL const char* U_EXPORT2 
+ures_getVersionNumberInternal(const UResourceBundle *resourceBundle);
+
+/**
+ * Return the name of the Locale associated with this ResourceBundle. This API allows
+ * you to query for the real locale of the resource. For example, if you requested 
+ * "en_US_CALIFORNIA" and only "en_US" bundle exists, "en_US" will be returned. 
+ * For subresources, the locale where this resource comes from will be returned.
+ * If fallback has occured, getLocale will reflect this.
+ *
+ * @param resourceBundle resource bundle in question
+ * @param status just for catching illegal arguments
+ * @return  A Locale name
+ * @deprecated ICU 2.8 Use ures_getLocaleByType instead.
+ */
+U_INTERNAL const char* U_EXPORT2 
+ures_getLocaleInternal(const UResourceBundle* resourceBundle, 
+               UErrorCode* status);
+
 #endif /*URESIMP_H*/
diff --git a/icu4c/source/common/ustrtrns.c b/icu4c/source/common/ustrtrns.c
index bae52675f35..aa18ef5bee2 100644
--- a/icu4c/source/common/ustrtrns.c
+++ b/icu4c/source/common/ustrtrns.c
@@ -1507,7 +1507,7 @@ u_strToJavaModifiedUTF8(
         int32_t srcLength,
         UErrorCode *pErrorCode) {
     int32_t reqLength=0;
-    uint32_t ch=0,ch2=0;
+    uint32_t ch=0;
     uint8_t *pDest = (uint8_t *)dest;
     uint8_t *pDestLimit = pDest + destCapacity;
     const UChar *pSrcLimit;
diff --git a/icu4c/source/common/utrie2.cpp b/icu4c/source/common/utrie2.cpp
index cfbc9ecb8ba..3e051bab4b7 100644
--- a/icu4c/source/common/utrie2.cpp
+++ b/icu4c/source/common/utrie2.cpp
@@ -143,7 +143,7 @@ utrie2_openFromSerialized(UTrie2ValueBits valueBits,
     }
 
     /* enough data for a trie header? */
-    if(length<sizeof(UTrie2Header)) {
+    if(length<(int32_t)sizeof(UTrie2Header)) {
         *pErrorCode=U_INVALID_FORMAT_ERROR;
         return 0;
     }
@@ -412,7 +412,7 @@ utrie2_swap(const UDataSwapper *ds,
     }
 
     /* setup and swapping */
-    if(length>=0 && length<sizeof(UTrie2Header)) {
+    if(length>=0 && length<(int32_t)sizeof(UTrie2Header)) {
         *pErrorCode=U_INDEX_OUTOFBOUNDS_ERROR;
         return 0;
     }
@@ -487,7 +487,7 @@ utrie2_swap(const UDataSwapper *ds,
 
 /* default UTrie2EnumValue() returns the input value itself */
 static uint32_t U_CALLCONV
-enumSameValue(const void *context, uint32_t value) {
+enumSameValue(const void * /*context*/, uint32_t value) {
     return value;
 }
 
diff --git a/icu4c/source/i18n/digitlst.cpp b/icu4c/source/i18n/digitlst.cpp
index 96b974f7a61..7e5eb8e1c1c 100644
--- a/icu4c/source/i18n/digitlst.cpp
+++ b/icu4c/source/i18n/digitlst.cpp
@@ -541,7 +541,7 @@ void DigitList::getDecimal(CharString &str, UErrorCode &status) {
     }
     U_ASSERT(capacity >= maxLength);
     uprv_decNumberToString(this->fDecNumber, buffer);
-    U_ASSERT(uprv_strlen(buffer) <= maxLength);
+    U_ASSERT((int32_t)uprv_strlen(buffer) <= maxLength);
     str.append(buffer, -1, status);
 }
 
diff --git a/icu4c/source/i18n/smpdtfmt.cpp b/icu4c/source/i18n/smpdtfmt.cpp
index 2c2808cc882..7564531a63b 100644
--- a/icu4c/source/i18n/smpdtfmt.cpp
+++ b/icu4c/source/i18n/smpdtfmt.cpp
@@ -1797,7 +1797,6 @@ SimpleDateFormat::parse(const UnicodeString& text, Calendar& cal, ParsePosition&
     int32_t abutStart = 0;
     int32_t abutPass = 0;
     UBool inQuote = FALSE;
-    UBool skipwhsp = FALSE;
 
     const UnicodeString numericFormatChars(NUMERIC_FORMAT_CHARS);
 
diff --git a/icu4c/source/i18n/ucol_imp.h b/icu4c/source/i18n/ucol_imp.h
index 63b54aff69a..b18f81200c1 100644
--- a/icu4c/source/i18n/ucol_imp.h
+++ b/icu4c/source/i18n/ucol_imp.h
@@ -373,6 +373,9 @@ struct UCollationElements : public U_NAMESPACE_QUALIFIER UMemory
         U_NAMESPACE_QUALIFIER UCollationPCE     *pce;
 };
 
+#else
+/*opaque type*/
+struct UCollationElements;
 #endif
 
 U_CAPI void U_EXPORT2
diff --git a/icu4c/source/i18n/ucol_wgt.cpp b/icu4c/source/i18n/ucol_wgt.cpp
index 56531d2156f..bc37e4b6b45 100644
--- a/icu4c/source/i18n/ucol_wgt.cpp
+++ b/icu4c/source/i18n/ucol_wgt.cpp
@@ -120,7 +120,7 @@ lengthenRange(WeightRange *range, uint32_t maxByte, uint32_t countBytes) {
 
 /* for uprv_sortArray: sort ranges in weight order */
 static int32_t U_CALLCONV
-compareRanges(const void *context, const void *left, const void *right) {
+compareRanges(const void * /*context*/, const void *left, const void *right) {
     uint32_t l, r;
 
     l=((const WeightRange *)left)->start;
diff --git a/icu4c/source/i18n/zonemeta.cpp b/icu4c/source/i18n/zonemeta.cpp
index 0332894d5a7..bf79109bd97 100644
--- a/icu4c/source/i18n/zonemeta.cpp
+++ b/icu4c/source/i18n/zonemeta.cpp
@@ -191,7 +191,7 @@ ZoneMeta::getCanonicalSystemID(const UnicodeString &tzid, UnicodeString &systemI
         // check canonical mapping in CLDR
         char id[ZID_KEY_MAX];
         int32_t len = u_strlen(canonical);
-        if (len < sizeof(id)) {
+        if (len < (int32_t)sizeof(id)) {
             u_UCharsToChars(canonical, id, len + 1 /* include the terminator */);
             // replace '/' with ':'
             char *p = id;
@@ -310,7 +310,7 @@ ZoneMeta::getSingleCountry(const UnicodeString &tzid, UnicodeString &country) {
             getCanonicalSystemID(*id, canonical, status);
             if (U_SUCCESS(status)) {
                 // check if there are any other canonical zone in the group
-                while (id = ids->snext(status)) {
+                while ((id = ids->snext(status))!=NULL) {
                     getCanonicalSystemID(*id, tmp, status);
                     if (U_FAILURE(status)) {
                         break;
diff --git a/icu4c/source/test/cintltst/ccapitst.c b/icu4c/source/test/cintltst/ccapitst.c
index c092f1bff6e..6d4ecd715df 100644
--- a/icu4c/source/test/cintltst/ccapitst.c
+++ b/icu4c/source/test/cintltst/ccapitst.c
@@ -2698,13 +2698,13 @@ static void TestConvertExFromUTF8_C5F0() {
     UErrorCode errorCode;
     int32_t i;
 
-    static const char bad_utf8[2]={ 0xC5, 0xF0 };
+    static const unsigned char bad_utf8[2]={ 0xC5, 0xF0 };
     /* Expect "&#65533;&#65533;" (2x U+FFFD as decimal NCRs) */
-    static const char twoNCRs[16]={
+    static const unsigned char twoNCRs[16]={
         0x26, 0x23, 0x36, 0x35, 0x35, 0x33, 0x33, 0x3B,
         0x26, 0x23, 0x36, 0x35, 0x35, 0x33, 0x33, 0x3B
     };
-    static const char twoFFFD[6]={
+    static const unsigned char twoFFFD[6]={
         (char)0xef, (char)0xbf, (char)0xbd,
         (char)0xef, (char)0xbf, (char)0xbd 
     };
diff --git a/icu4c/source/test/cintltst/nucnvtst.c b/icu4c/source/test/cintltst/nucnvtst.c
index e3d99a9126c..399bc76ea99 100644
--- a/icu4c/source/test/cintltst/nucnvtst.c
+++ b/icu4c/source/test/cintltst/nucnvtst.c
@@ -65,7 +65,12 @@ static void TestISO_2022_JP_2(void);
 static void TestISO_2022_KR(void);
 static void TestISO_2022_KR_1(void);
 static void TestISO_2022_CN(void);
+#if 0
+   /*
+    * ICU 4.4 (ticket #7314) removes mappings for CNS 11643 planes 3..7
+    */
 static void TestISO_2022_CN_EXT(void);
+#endif
 static void TestJIS(void);
 static void TestHZ(void);
 #endif
@@ -78,7 +83,12 @@ static void TestGB18030(void);
 static void TestLMBCS(void);
 static void TestJitterbug255(void);
 static void TestEBCDICUS4XML(void);
+#if 0
+   /*
+    * ICU 4.4 (ticket #7314) removes mappings for CNS 11643 planes 3..7
+    */
 static void TestJitterbug915(void);
+#endif
 static void TestISCII(void);
 
 static void TestCoverageMBCS(void);
@@ -4235,6 +4245,10 @@ TestJIS(){
 
 }
 
+
+#if 0
+ ICU 4.4 (ticket #7314) removes mappings for CNS 11643 planes 3..7
+
 static void TestJitterbug915(){
 /* tests for roundtripping of the below sequence
 \x1b$)G\x0E#!#"###$#%#&#'#(#)#*#+          / *plane 1 * /
@@ -4422,6 +4436,7 @@ TestISO_2022_CN_EXT() {
     free(cBuf);
     free(offsets);
 }
+#endif
 
 static void
 TestISO_2022_CN() {
diff --git a/icu4c/source/test/intltest/apicoll.cpp b/icu4c/source/test/intltest/apicoll.cpp
index cdb91981765..4363880024e 100644
--- a/icu4c/source/test/intltest/apicoll.cpp
+++ b/icu4c/source/test/intltest/apicoll.cpp
@@ -1,6 +1,6 @@
 /********************************************************************
  * COPYRIGHT:
- * Copyright (c) 1997-2009, International Business Machines Corporation and
+ * Copyright (c) 1997-2010, International Business Machines Corporation and
  * others. All Rights Reserved.
  ********************************************************************/
 //===============================================================================
@@ -137,7 +137,7 @@ CollationAPITest::TestProperty(/* char* par */)
     doAssert((col->compare("blackbird", "black-bird") == Collator::GREATER), "black-bird > blackbird comparison failed");
     doAssert((col->compare("black bird", "black-bird") == Collator::LESS), "black bird > black-bird comparison failed");
     doAssert((col->compare("Hello", "hello") == Collator::GREATER), "Hello > hello comparison failed");
-    doAssert((col->compare("","",success) == Collator::EQUAL), "Comparison between empty strings failed");
+    doAssert((col->compare("","",success) == UCOL_EQUAL), "Comparison between empty strings failed");
 
     doAssert((col->compareUTF8("\x61\x62\xc3\xa4", "\x61\x62\xc3\x9f", success) == UCOL_LESS), "ab a-umlaut < ab sharp-s UTF-8 comparison failed");
     success = U_ZERO_ERROR;
diff --git a/icu4c/source/test/intltest/bidiconf.cpp b/icu4c/source/test/intltest/bidiconf.cpp
index 561c237d15c..48fa5c0bd96 100644
--- a/icu4c/source/test/intltest/bidiconf.cpp
+++ b/icu4c/source/test/intltest/bidiconf.cpp
@@ -1,7 +1,7 @@
 /*
 *******************************************************************************
 *
-*   Copyright (C) 2009, International Business Machines
+*   Copyright (C) 2009-2010, International Business Machines
 *   Corporation and others.  All Rights Reserved.
 *
 *******************************************************************************
@@ -65,7 +65,7 @@ extern IntlTest *createBiDiConformanceTest() {
     return new BiDiConformanceTest();
 }
 
-void BiDiConformanceTest::runIndexedTest(int32_t index, UBool exec, const char *&name, char *par) {
+void BiDiConformanceTest::runIndexedTest(int32_t index, UBool exec, const char *&name, char * /*par*/) {
     if(exec) {
         logln("TestSuite BiDiConformanceTest: ");
     }
@@ -180,7 +180,7 @@ static const UChar charFromBiDiClass[U_CHAR_DIRECTION_COUNT]={
 U_CDECL_BEGIN
 
 static UCharDirection U_CALLCONV
-biDiConfUBiDiClassCallback(const void *context, UChar32 c) {
+biDiConfUBiDiClassCallback(const void * /*context*/, UChar32 c) {
     for(int i=0; i<U_CHAR_DIRECTION_COUNT; ++i) {
         if(c==charFromBiDiClass[i]) {
             return (UCharDirection)i;
diff --git a/icu4c/source/test/intltest/callimts.cpp b/icu4c/source/test/intltest/callimts.cpp
index 9e21bf4e58f..ed583ef07db 100644
--- a/icu4c/source/test/intltest/callimts.cpp
+++ b/icu4c/source/test/intltest/callimts.cpp
@@ -163,7 +163,7 @@ CalendarLimitTest::TestLimits(void) {
         {"coptic",          FALSE,      DEFAULT_START, DEFAULT_END},
         {"ethiopic",        FALSE,      DEFAULT_START, DEFAULT_END},
         {"ethiopic-amete-alem", FALSE,  DEFAULT_START, DEFAULT_END},
-        {NULL,              FALSE,      0.0}
+        {NULL,              FALSE,      0, 0}
     };
 
     int16_t i = 0;
diff --git a/icu4c/source/test/intltest/dcfmtest.cpp b/icu4c/source/test/intltest/dcfmtest.cpp
index 5cf0aafcc0e..41983574e9b 100644
--- a/icu4c/source/test/intltest/dcfmtest.cpp
+++ b/icu4c/source/test/intltest/dcfmtest.cpp
@@ -409,7 +409,7 @@ void DecimalFormatTest::execFormatTest(int32_t lineNum,
 
     Formattable fmtbl;
     fmtbl.setDecimalNumber(spInput, status);
-    NumberFormat &nfmtr = fmtr;
+    //NumberFormat &nfmtr = fmtr;
     fmtr.format(fmtbl, result, NULL, status);
 
     if (U_FAILURE(status)) {
diff --git a/icu4c/source/test/intltest/numfmtst.cpp b/icu4c/source/test/intltest/numfmtst.cpp
index c586c9654b5..b1ea42e776b 100644
--- a/icu4c/source/test/intltest/numfmtst.cpp
+++ b/icu4c/source/test/intltest/numfmtst.cpp
@@ -2817,7 +2817,7 @@ NumberFormatTest::TestCurrencyFormatForMixParsing() {
         "US dollars1,234.56",
         "1,234.56 US dollars"
     };
-    const CurrencyAmount* curramt;
+    const CurrencyAmount* curramt = NULL;
     for (uint32_t i = 0; i < sizeof(formats)/sizeof(formats[0]); ++i) {
         UnicodeString stringToBeParsed = ctou(formats[i]);
         Formattable result;
diff --git a/icu4c/source/test/intltest/rbbitst.cpp b/icu4c/source/test/intltest/rbbitst.cpp
index b2d09943ebb..7fc36ef7e2b 100644
--- a/icu4c/source/test/intltest/rbbitst.cpp
+++ b/icu4c/source/test/intltest/rbbitst.cpp
@@ -1959,8 +1959,8 @@ void RBBITest::TestTailoredBreaks() {
     Locale rootLocale = Locale("root");
     for (tbItemPtr = tbItems; tbItemPtr->escapedText != NULL; ++tbItemPtr) {
         Locale testLocale = Locale(tbItemPtr->locale);
-        BreakIterator * tailoredBrkiter;
-        BreakIterator * rootBrkiter;
+        BreakIterator * tailoredBrkiter = NULL;
+        BreakIterator * rootBrkiter = NULL;
         UErrorCode status = U_ZERO_ERROR;
         switch (tbItemPtr->type) {
             case UBRK_CHARACTER:
diff --git a/icu4c/source/test/intltest/regcoll.cpp b/icu4c/source/test/intltest/regcoll.cpp
index 9ea2cd3f0dd..2e077d35116 100644
--- a/icu4c/source/test/intltest/regcoll.cpp
+++ b/icu4c/source/test/intltest/regcoll.cpp
@@ -1,6 +1,6 @@
 /********************************************************************
  * COPYRIGHT:
- * Copyright (c) 1997-2009, International Business Machines Corporation and
+ * Copyright (c) 1997-2010, International Business Machines Corporation and
  * others. All Rights Reserved.
  ********************************************************************/
 
@@ -1081,7 +1081,7 @@ void CollationRegressionTest::Test4146160(/* char* par */)
 // Ticket 7189
 //
 // nextSortKeyPart incorrect for EO_S1 collation
-static int32_t calcKeyIncremental(UCollator *coll, const UChar* text, int32_t len, uint8_t *keyBuf, int32_t keyBufLen, UErrorCode& status) {
+static int32_t calcKeyIncremental(UCollator *coll, const UChar* text, int32_t len, uint8_t *keyBuf, int32_t /*keyBufLen*/, UErrorCode& status) {
     UCharIterator uiter;
     uint32_t state[2] = { 0, 0 };
     int32_t keyLen;
diff --git a/icu4c/source/test/intltest/selfmts.cpp b/icu4c/source/test/intltest/selfmts.cpp
index e81d44fe553..31b39ae11e2 100644
--- a/icu4c/source/test/intltest/selfmts.cpp
+++ b/icu4c/source/test/intltest/selfmts.cpp
@@ -190,7 +190,7 @@ void SelectFormatTest::selectFormatAPITest(/*char *par*/)
 {
     int numOfConstructors =3;
     UErrorCode status[3];
-    SelectFormat* selFmt[3];
+    SelectFormat* selFmt[3] = { NULL, NULL, NULL };
 
     // ========= Test constructors
     logln("SelectFormat API test: Testing SelectFormat constructors ...");
@@ -221,7 +221,13 @@ void SelectFormatTest::selectFormatAPITest(/*char *par*/)
             if ( *selFmt[1] != *selFmt[0] ) {
                 errln("ERROR: SelectFormat API test clone test failed!");
             }
+        } else {
+          errln("ERROR: SelectFormat API test clone test failed with NULL!");
+          return;
         }
+    } else {
+      errln("ERROR: could not create [0]: %s\n", u_errorName(status[0]));
+      return;
     }
 
     // ======= Test assignment operator && == operator.
diff --git a/icu4c/source/test/intltest/tstnorm.cpp b/icu4c/source/test/intltest/tstnorm.cpp
index dd4e402c892..77c621aa3f7 100644
--- a/icu4c/source/test/intltest/tstnorm.cpp
+++ b/icu4c/source/test/intltest/tstnorm.cpp
@@ -1705,27 +1705,6 @@ initExpectedSkippables(UnicodeSet skipSets[UNORM_MODE_COUNT]) {
         , ""), errorCode);
 }
 
-U_CDECL_BEGIN
-
-// USetAdder implementation
-// Does not use uset.h to reduce code dependencies
-static void U_CALLCONV
-_set_add(USet *set, UChar32 c) {
-    uset_add(set, c);
-}
-
-static void U_CALLCONV
-_set_addRange(USet *set, UChar32 start, UChar32 end) {
-    uset_addRange(set, start, end);
-}
-
-static void U_CALLCONV
-_set_addString(USet *set, const UChar *str, int32_t length) {
-    uset_addString(set, str, length);
-}
-
-U_CDECL_END
-
 void
 BasicNormalizerTest::TestSkippable() {
     UnicodeSet diff, skipSets[UNORM_MODE_COUNT], expectSets[UNORM_MODE_COUNT];
diff --git a/icu4c/source/test/intltest/tzfmttst.cpp b/icu4c/source/test/intltest/tzfmttst.cpp
index ee8dc000bcd..6ea01d4c9e5 100644
--- a/icu4c/source/test/intltest/tzfmttst.cpp
+++ b/icu4c/source/test/intltest/tzfmttst.cpp
@@ -287,7 +287,6 @@ public:
         }
 
         int32_t testCounts = 0;
-        UBool done = false;
 
         while (true) {
             umtx_lock(NULL); // Lock to increment the index
diff --git a/icu4c/source/tools/ctestfw/ucln_ct.c b/icu4c/source/tools/ctestfw/ucln_ct.c
index 1f4bbbed36a..ae0a22571c3 100644
--- a/icu4c/source/tools/ctestfw/ucln_ct.c
+++ b/icu4c/source/tools/ctestfw/ucln_ct.c
@@ -1,6 +1,6 @@
 /********************************************************************
  * COPYRIGHT:
- * Copyright (c) 2007-2009, International Business Machines Corporation and
+ * Copyright (c) 2007-2010, International Business Machines Corporation and
  * others. All Rights Reserved.
  ********************************************************************/
 
@@ -9,8 +9,8 @@
 #define UCLN_TYPE UCLN_CTESTFW
 #include "ucln_imp.h"
 
-int dummyFunction();
-int dummyFunction()
+int dummyFunction(void);
+int dummyFunction(void)
 {
   /* this is here to prevent the compiler from complaining about an empty file */
   return 0;
diff --git a/icu4c/source/tools/icuinfo/icuinfo.cpp b/icu4c/source/tools/icuinfo/icuinfo.cpp
index 0e7f0711c1d..4144570f1bc 100644
--- a/icu4c/source/tools/icuinfo/icuinfo.cpp
+++ b/icu4c/source/tools/icuinfo/icuinfo.cpp
@@ -81,7 +81,6 @@ void cmd_millis()
 void cmd_version(UBool noLoad)
 {
     UVersionInfo icu;
-    UErrorCode status = U_ZERO_ERROR;
     char str[200];
     printf("<ICUINFO>\n");
     printf("International Components for Unicode for C/C++\n");
diff --git a/icu4c/source/tools/toolutil/ucln_tu.c b/icu4c/source/tools/toolutil/ucln_tu.c
index f3d43b4d1a0..7c7f5052cc8 100644
--- a/icu4c/source/tools/toolutil/ucln_tu.c
+++ b/icu4c/source/tools/toolutil/ucln_tu.c
@@ -9,8 +9,8 @@
 #define UCLN_TYPE UCLN_TOOLUTIL
 #include "ucln_imp.h"
 
-int dummyFunction();
-int dummyFunction()
+int dummyFunction(void);
+int dummyFunction(void)
 {
   /* this is here to prevent the compiler from complaining about an empty file */
   return 0;