Poly(ethylene terephthalate) (PET) fibers were treated with Co-60-gamma-ray and grafted with acrylic acid. The resulting fibers were further grafted with chitosan (CS) via esterification. Afterward, hyaluronic acid (HA) was immobilized onto CS-grafting fibers. The antibacterial activity of CS against S. aureus, E. coli, and P. aeruginosa was preserved after HA-immobilization. After immobilizing HA, the L929 fibroblasts cell proliferation was improved for CS-grafting PET fiber. The results indicate that by grafting with CS and immobilizing with HA, PET fibers not only exhibit antibacterial activity, but also improve the cell proliferation for fibroblast. (c) 2007 Wiley Periodicals, Inc.