Abstract: This invention relates to a method for sterilization, by irradiation with .gamma.-ray, of a hydrogel obtained by freezing an aqueous polyvinyl alcohol solution and then thawing it or by partially dehydrating (3% or more in weight reduction rate of the frozen body) the aqueous polyvinyl alcohol solution as it is frozen under vacuum and by selecting dosage of the .gamma.-ray of 3-10 Mrad, stable sterilization effect can be obtained with less soluble decomposition products. Especially, this method is effective and most suitable as a method for sterilization of polyvinyl alcohol hydrogel molded article for medical use.

Abstract: A process for producing a medical material having high anti-thrombogenicity that is suitable for use in catheters and other medical devices in contact with blood flowing in circulatory organs and other tissues is disclosed. According to this process, an acrylamide or methacrylamide derivative having a tertiary amino group, or an unsaturated monomer having a hydrophihlic group and the ability to promote copolymerization, or a mixture thereof is graft polymerized onto a polyurethane elastomeric or polyolefinic high-molecular weight substrate with an ionizing radiation.