D:\c\whereis>cl testBoost.cpp Microsoft (R) 32-bit C/C++ Optimizing Compiler Version 13.10.3077 for 80x86 Copyright (C) Microsoft Corporation 1984-2002. All rights reserved. testBoost.cpp testBoost.cpp(5) : fatal error C1083: Cannot open include file: 'boost/regex.hpp': No such file or directory D:\c\whereis>set include INCLUDE=E:\Program Files\Microsoft Visual Studio .NET 2003\VC7\ATLMFC\INCLUDE;E:\Program Files\Microsoft Visual Studio .NET 2003\VC7\INCLUDE;E:\Program Files\Microsoft Visual Studio .NET 2003\VC7\PlatformSDK\include\prerelease;E:\Program Files\Microsoft Visual Studio .NET 2003\VC7\PlatformSDK\include;E:\Program Files\Microsoft Visual Studio .NET 2003\SDK\v1.1\include;C:\Program Files\Microsoft Visual Studio .NET 2003\SDK\v1.1\include\;C:\Program Files\Microsoft Visual Studio .NET\FrameworkSDK\include\;C:\Boost\include\boost-1_32\boost D:\c\whereis>dir C:\Boost\include\boost-1_32\boost\regex.hpp Volume in drive C is SYSXP Volume Serial Number is 6B12-D3A9 Directory of C:\Boost\include\boost-1_32\boost 10/04/2003 06:28 941 regex.hpp 1 File(s) 941 bytes 0 Dir(s) 472,326,144 bytes free D:\c\whereis>set BOOST_ROOT BOOST_ROOT=C:\Boost\include\boost-1_32 AFAICT the above shows the cl compiler can't find boost/regex.hpp, however the include path lists the correct location, regex.hpp shows up in a directory listing, and BOOST_ROOT is correctly set. What's going on? Something stupid perhaps. -frank brown http://www.inwa.net/~frog