Thin, biocompatible, high-strength, composite materials are disclosed that are suitable for use in a prosthetic valve for regulating blood flow direction. In one aspect, the leaflet material maintains flexibility in high-cycle flexural applications, making it particularly applicable to high-flex implants such as a prosthetic heart valve leaflet. The leaflet material includes a coherent single layer and an elastomer, wherein the elastomer is present in the pores of the porous coherent single layer.