Zabin, The QDoubleValidator class works, but it allows 'intermediate' values to show in the widget. This problem has been addressed here: http://qt.nokia.com/developer/faqs/faq.2006-05-15.0450651751, I just tried to implement this in PyQt again, and it worked! =P I've posted the working code here: http://learnwithhelvin.blogspot.com/2010/01/qdoublevalidator.html Helvin