Polypropylene dialysis membranes were prepared using cobalt-60 gamma radiation to directly graft 2-hydroxyethyl methacrylate (HEMA) onto polypropylene (PP) membranes. The surface structures of both the grafted membranes and the PP membrane were observed by using FTIR-PAS and ESCA methods. The X-ray diffraction diagrams of the PP and PP-g-HEMA membranes indicated a transformation process of the p-form toward the ct-form crystallinity with increasing degree of grafting. The SEM data of the membrane grafted under a low grafting temperature showed many spheres of PHEMA embedded in the PP matrix, whose size was well distributed and increased with the degree of grafting. The influences of the degree of grafting and grafting temperature on the permeabilities of PP-g-HEMA membranes toward urea and creatinine were studied in a dialyzer. In all cases, the PP-g-HEMA membrane obtained under higher grafting temperature showed higher permeability toward those solutes. The permeation coefficients of urea and creatinine through the PP-g-HEMA membrane obtained at 59 degrees C were about 10.4 and 28.8 times that through the PP membrane, respectively.