Confirmed that the latest lxml still has some problem on OS X. Python 2.5.1 (r251:54863, Feb 2 2008, 17:46:03) [GCC 4.0.1 (Apple Computer, Inc. build 5363)] on darwin Type "help", "copyright", "credits" or "license" for more information. >>> import webbrowser >>> from lxml import etree, html zsh: bus error python2.5