2,3-epoxypropyl methacrylate(EPMA) was grafted to polypropylene(PP) film by using radiation grafting technique. The phosphoric acid group was introduced EPMA-grafted PP films with different grafting yields. The EPMA grafting extent was found to be dependent on the absorbed dose, reaction time, and temperature. The grafting and phophonation were confirmed by Fourier transform infrared spectroscopy in the attenuated total reflectance mode(FTIR-ATR) and electron spectroscopy for chemical analysis(ESCA). For examination of blood compatibility of samples prepared, acid citrate dextrose(ACD) human whole blood, platelet rich plasma(PRP), and platelet poor plasma(PPP) were used. The amount of thrombus formed and adherent platelet on PP sample surfaces were evaluated by an in vitro method following Imai and Nose technique and by scanning electron microscope(SEM), respectively.