Comment #1 on issue 126 by cjlee112: pygr requires 10.4 SDK on Mac OS X 10.6 http://code.google.com/p/pygr/issues/detail?id=126 Doesn't replicate for me on Mac OS 10.6.4 10.6 SDK version 10M2423 /usr/bin/python setup.py build succeeds normally for me.