The purpose of this study was to enhance blood compatibility of polyethylene (PE) films. Glycidyl methacrylate (GMA) was grafted onto the surface of PE by Ar plasma pretreatment and UV-induced graft polymerization without photo-initiator, then heparin was immobilized onto the poly (glycidyl methacrylate) segments. The surface compositions and microstructure of GMA graft polymerized PE films were studied by X-ray photoelectron spectroscopy (XPS) and Attenuated Total Reflectance Fourier Transfer Infrared (ATR-FTIR) spectroscopy. It was confirmed that heparin was successfully immobilized onto the surface of PE films by XPS analysis. The antithrombogenicity of the samples was determined by the activated partial thromboplastin time (APTT), prothrombin time (PT), thrombin time (TT), and plasma recalcification time (PRT) tests and platelet adhesion experiment. Results indicated that the antithrombogenicity of modified PE was improved remarkably. (C) 2004 Wiley Periodicals, Inc.