>If you mean the close button of the form then use the queryunload event like Cetin said.
>If you return .f. there the unload will stop.

Ko, I'm not sure where this idea ("return .f.") got started (I've seen it posted several times before, in fact), but I've never observed this to work at all. The only certain way to stop the form is a

NoDefault

in the Queryunload. If someone can show me an instance or vfp version where return .f. works, I will humbly eat some metaphorical hat...