The present invention is directed to a medical electrical lead including an insulative lead body formed, at least in part, from a polyisobutylene urethane, urea or urethane/urea copolymer. In some applications, the lead body can include at least one outer tubular insulator and/or an inner elongated member formed from a polyisobutylene urethane, urea or urethane/urea copolymer. Portions of the lead body formed form the polyisobutylene urethane, urea or urethane/urea copolymer can be either extruded or molded.
