eps without figure frame

Hi,
I'm trying to create an eps file which does not have a figure frame. I used
figurePatch.fill = False
to prevent filling but there's still a white frame drawn around the figure which
is visible when putting it on a coloured background.

figurePatch.set_lw(0.0)
didn't help neither.

figure(frameon=False)
seems to have no effect.

Thank you in advance, Christian