In this work, poly(vinyl alcohol)/polyvinylpyrrolidone (PVA/PVP) hydrogels were prepared by cycled freezing and thawing process, and subsequently with irradiation crosslink processing. The exterior microstructure and frictional coefficients of compound hydrogels with and without radiation treatment were compared. The changes of surface lubricative properties were observed in physiological condition in vitro. Without radiation treatment, the friction coefficient of PVA/PVP hydrogels increased rapidly in water because of the solubility and exudation of PVP, which could induce the decline of their lubricative action. While after radiation treatment, the surface lubricative properties of PVA/PVP hydrogels in water were improved and stable due to the crosslink between PVA and PVP. (c) 2008 Elsevier B.V. All rights reserved.