The warranty for the Intellimouse Explorer is lifetime, or at least it was a few months ago when I needed to use it. I had one go bad. The pointer would just vibrate on the screen. Called MS. They sent me a new mouse. I did not have to return the old one. I just threw it in the trash. A few months later, the replacement went bad too. The cable had an intermittent open so the o/s was always detecting "new hardware" as if you were plugging/unplugging the mouse. Called them up again. Same deal, they sent me a new one and I threw the old one in the trash. Did not have to RMA anything. Just confirmed it was bad with the tech support guy, got sent a new one, and threw out the bad one. Both times it was that simple.