> just return the "Simple pointInPoly() test..." > no return from point_inside_polygon(3,10,poly) ---------------- if __name__ == '__main__': print 'Simple pointInPoly() test...' poly = [(-1,-1), (6,-1), (5,6), (0,5)] point_inside_polygon(3,10,poly) ----------------- You need to print it to see it.... The function returns a value which you ignore. Alan G.