if the string you want to match (not the regular expression string) contains characters with code >= 128 then CAtlRegExp::Match() method fails. Here is the fix suggested here: http://groups-beta.google.com/group/microsoft.public.vc.atl/msg/b525c84477676c4f Hi, I was running in the same problem with german umlauts. The algorithm seems to be buggy. To word around that, copy the file C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7\atlmfc\include\atlrx.h to your project path and make the following changes and include it in your cpp: Line 637 New code: unsigned char* usz = (unsigned char *) sz; size_t u = (size_t) *usz; instead of Old code: size_t u = (size_t) *sz; and Line 1181 New code: unsigned char uchStart = chStart; unsigned char uchEnd = chEnd; for (int i=uchStart; i instead of Old code: for (int i=chStart; i