A sterilization process that preserves the mechanical properties of dilatation balloons and balloon catheters manufactured from polymers susceptible to the degradation reactions induced by ionizing radiation. The advantages of the sterilization process contemplated by this invention results from a reduced oxygen environment during sterilization, thereby preventing the degeneration process initiated in polymers during irradiation. Additionally, a balloon or balloon dilatation catheter sterilized by the process of the invention is provided.