The antibacterial properties of medical polyethylene (PE) were enhanced by coating with triclosan or bronopol and plasma immersion ion implantation (Pill). 02 plasma was first employed to produce a more hydrophilic surface on the PE, followed by argon or hydrogen plasma treatment to enhance the coating of triclosan or bronopol onto the surface. The modified surfaces were characterized by XPS, FIFIR, SEM, and contact angle measurements. The antibacterial properties were evaluated utilizing the method of plate-counting of Staphylococcus aureus (Gram positive) and Escherichia coli (Gram negative). Our experimental results show that the plasma-modified PE with triclosan exhibits excellent antibacterial properties. Even after 6 weeks, the antibacterial effects against E. coli and S. aureus remain at high levels of 99.9 and 68.4%. The plasma-modified PE with bronopol has better antibacterial performances against E. coli and S. aureus in the beginning. Afterwards, the antibacterial effects degrade relatively rapidly. Our results reveal that non-reactive argon plasma was better than reactive hydrogen plasma in improving the antibacterial properties of PE. Bacterial adhesion on the modified samples was also investigated and the number of active adhered bacteria was observed to be always low. (c) 2005 Elsevier Ltd. All rights reserved.