A medical device, and particularly an intracorporeal device for therapeutic or diagnostic use, comprising a silicone polyurethane. One embodiment of the invention is a medical device having a body formed of melt process extruded, porous silicone polyurethane material. In a method of the invention, the silicone polyurethane is combined with a porogen and then melt process extruded into a desired shape such as a tubular body. The porogen is then extracted from the extrudate, to form the extruded, melt processed, porous silicone polyurethane tubular body. The medical device, such as a stent cover, vascular graft, or catheter balloon, formed of the silicone polyurethane has excellent biostability, strength, and flexibility.