I am getting the following 7 link errors while making a release build of my application. (I have no problem making a debug build).

Any idea why these function calls failed to be linked. (does it has to do with the calling convention __fastcall being changed to __stdcall?)

Does .NET support __fastcall at all? If not then that is the cause of the problem.

I have tried making BOOST_REGEX_CALL __cdecl to no avail.

Try opening up boost/regex/config.hpp and changing: # define BOOST_REGEX_CALL __fastcall to # define BOOST_REGEX_CALL __cdecl Then rebuild *both* the regex libraries, and your application. Let me know if this helps at all, John.