Hello, I have written replacements for a few of Mark Hammond's PyWin32 functions using ctypes to call upon the Windows kernel API. Code can be found here; http://pastebin.com/m46de01f . When calling ReadFile, it appears that the kernel API converts '/n' newlines '/r/n' newlines. I have not been able to find any information about this but as far as I can tell, there is nothing in my code that is causing the problem. Initially I suspected it related to newline translation but the function in subprocess.Popen for translating newlines only converts to '/n' newlines. When I replaced my ReadFile and WriteFile functions with the PyWin32 functions I was imitating, the problem still arose. I was hoping someone could confirm this problem for me from experience or by testing out my code. If you would like the see the functions used in full context, I have a Mercurial Google Code project that can be checked out at http://code.google.com/p/subprocdev/source/list(branch "python3k"). My work entails modifications to subprocess.py so when running the code, please update your PYTHONPATH variable so that my subprocess.py will be imported. Eric