People, this is one of the errors I got when compiling boost regex with vc7.1 + stlport: vc-Link bin\boost\libs\regex\build\boost_regex.dll\vc7.1-stlport\release\boost_regex-vc71-mt-p-1_31.dll bin\boost\libs\regex\build\boost_regex.dll\vc7.1-stlport\release\boost_regex-vc71-mt-p-1_31.lib Creating library bin\boost\libs\regex\build\boost_regex.dll\vc7.1-stlport\release\boost_regex-vc71-mt-p-1_31.lib and object bin\boost\libs\regex\build\boost_regex.dll\vc7.1-stlport\release\boost_regex-vc71-mt-p-1_31.exp winstances.obj : error LNK2001: unresolved external symbol "private: unsigned int __fastcall boost::cpp_regex_traits<wchar_t>::do_syntax_type(unsigned int)const " (?do_syntax_type@?$cpp_regex_traits@_W@boost@@ABIII@Z) regex.obj : error LNK2001: unresolved external symbol "private: unsigned int __fastcall boost::cpp_regex_traits<wchar_t>::do_syntax_type(unsigned int)const " (?do_syntax_type@?$cpp_regex_traits@_W@boost@@ABIII@Z) w32_regex_traits.obj : error LNK2001: unresolved external symbol "private: unsigned int __fastcall boost::cpp_regex_traits<wchar_t>::do_syntax_type(unsigned int)const " (?do_syntax_type@?$cpp_regex_traits@_W@boost@@ABIII@Z) wide_posix_api.obj : error LNK2001: unresolved external symbol "private: unsigned int __fastcall boost::cpp_regex_traits<wchar_t>::do_syntax_type(unsigned int)const " (?do_syntax_type@?$cpp_regex_traits@_W@boost@@ABIII@Z) instances.obj : error LNK2001: unresolved external symbol "private: unsigned int __fastcall boost::cpp_regex_traits<wchar_t>::do_syntax_type(unsigned int)const " (?do_syntax_type@?$cpp_regex_traits@_W@boost@@ABIII@Z) c_regex_traits.obj : error LNK2019: unresolved external symbol "private: unsigned int __fastcall boost::cpp_regex_traits<wchar_t>::do_syntax_type(unsigned int)const " (?do_syntax_type@?$cpp_regex_traits@_W@boost@@ABIII@Z) referenced in function "public: unsigned int __fastcall boost::cpp_regex_traits<wchar_t>::syntax_type(unsigned int)const " (?syntax_type@?$cpp_regex_traits@_W@boost@@QBIII@Z) c_regex_traits_common.obj : error LNK2001: unresolved external symbol "private: unsigned int __fastcall boost::cpp_regex_traits<wchar_t>::do_syntax_type(unsigned int)const " (?do_syntax_type@?$cpp_regex_traits@_W@boost@@ABIII@Z) cregex.obj : error LNK2001: unresolved external symbol "private: unsigned int __fastcall boost::cpp_regex_traits<wchar_t>::do_syntax_type(unsigned int)const " (?do_syntax_type@?$cpp_regex_traits@_W@boost@@ABIII@Z) posix_api.obj : error LNK2001: unresolved external symbol "private: unsigned int __fastcall boost::cpp_regex_traits<wchar_t>::do_syntax_type(unsigned int)const " (?do_syntax_type@?$cpp_regex_traits@_W@boost@@ABIII@Z) bin\boost\libs\regex\build\boost_regex.dll\vc7.1-stlport\release\boost_regex-vc71-mt-p-1_31.dll : fatal error LNK1120: 1 unresolved externals The odd thing is that when i compile boost withou stlport included it does not generate this erros, but it would be perfect to have stlport+boost Any ideas? Thanks in advance, Rodrigo