A thin, biocompatible, high-strength, composite material is disclosed that is suitable for use in various implanted configurations. In one aspect, the composite material maintains flexibility in high-cycle flexural applications, making it particularly applicable to high-flex implants such as heart pacing lead or heart valve leaflet. The composite material includes a porous expanded fluoropolymer membrane and an elastomer, wherein the elastomer fills substantially all of the pores of the porous expanded fluoropolymer, and the composite material comprising less than about 80% fluoropolymer by weight.