Methacrylic acid (MAAc) could be effectively graft-polymerized onto the surface of poly (ethylene terephthalate) (PET) by UV irradiation without any photo-initiator and degassing process. The density of grafted poly (methacrylic acid) (PMAAc) increased with irradiation time and monomer concentration. The water contact angle of the grafted surface decreased from 70 to 45° and leveled off at graft densities higher than 1.5μg/cm². High wettability of the film surface was achieved by the grafting of PMAAc. The grafted layer was found to locate on the surface region of the film, and the thickness of the layer was about 310 nm when the graft density was 14 μg/cm². There was no clear difference in the SEM between the grafted and the ungrafted PET fabrics. An antibacterial property of PET fabric was easily accomplished by immersing the grafted fabric in 2 wt% aqueous solution of copper (II) acetate. The introduction of Cu ions onto the grafted PET surface was confirmed by XPS. Bactericidal tests showed that a good antibacterial property of the Cu⁺²-treated fabrics was maintained even after washing with 0.2 wt% marseille soap aqueous solution at 100°C for 10 min.