Graft copolymerization of acrylamide onto polyethylene terephthalate (PET) using a CO2 pulsed laser was performed to improve water wettability. After laser irradiation in air, the films were placed in the aqueous solution of monomer and then heated to decompose peroxides formed onto the irradiated PET film. Peroxide density was determined spectrophotometrically by means of the iodide method. The grafted PET surfaces were characterized by attenuated total reflectance infrared spectroscopy, scanning electron microscopy, and contact angle measurements. The electron micrographs showed that the grafting changed the surface morphology of the PET film, which is consistent with the infrared spectra of the grafted films. To evaluate the surface hydrophilicity, water drop contact angle was determined. The contact angle decreased as a result of graft polymerization. It was also found that the hydrophilicity is related to the surface morphology and grafting level. (C) 2000 John Wiley & Sons, Inc.