Ultra-high molecular weight polyethylene (UHMWPE) was prepared by thermal compression molding method and was irradiated by gamma rays at dose of 100 kGy in air. The wettability and water absorption of non-irradiated and irradiation crosslinked UHMWPE were investigated. It was shown that irradiation crosslinking increased the wettability of UHMWPE. The water absorption rate of UHMWPE was extremely low (<0.02%). After irradiation crosslinking, the water absorption rate of UHMWPE increased.