Abstract This paper describes research to improve the blood compatibility of polyethylene (PE) film. O-Butyrylchitosan (OBCS) was grafted to PE film by using a radiation grafting technique. The grafted sample films were verified by attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), electron spectroscopy for chemical analysis (ESCA) and the water contact angle measurements. The blood compatibility of the OBCS-grafted PE films was evaluated by platelet-rich plasma (PRP) contacting experiments and protein adsorption experiments that the results were described. The blood compatibility of OBCS-grafted PE film is better than that of blank PE film. These results suggest that the photocrosslinkable chitosan developed here has the potential of serving in blood-contacting applications in medical use.