Hello, i changed Python 2.3 to Python 2.1. The ftp of python.org contains a *.zip file in the 2.1 directory which contains python21_d.lib etc. I downloaded the file, and unpacked it in my python21 directory. http://www.python.org/ftp/python/2.1/Python-2.1-Debug.zip Now PyRun_SimpleFile works !! Thanks!!!!! Bye Susanne