The present invention relates generally to radiation-resistant medical devices which contain polymer regions for release of therapeutic agents. The present invention also relates to radiation-resistant block copolymer materials for use in connection with insertable or implantable medical devices. The radiation-sterilized medical device comprise (a) a release region and (b) at least one therapeutic agent and the release region comprises a radiation resistant copolymer that includes (i) a low T.sub.g hydrocarbon polymer block and (ii) one or more high T.sub.g polymer blocks.