I guess you're trying to install php on Windows and I had the same problem until I read the instructions again on the Downloads page of windows.php.net. The version you want is the VC6 thread-safe one not one of the VC9 versions. The VC6 zip version does contain the .dll you want and it works whereas the VC9 version does not have it. The first is compiled (from C I guess) under the old Visual Studio 6. It is recommended to run on Windows whereas the VC9 (compiled under Visual Studio 9 - .net 2008) is not recommended - figure that!