The grafting of acrylic acid (AA) onto biaxially oriented nylon 6 film has been investigated by simultaneous irradiation technique in the aqueous solution in the presence of benzophenone (BP) as a photosensitizer. The effects of various reaction conditions involving monomer concentration, photosensitizer concentration, reaction time and temperature were studied. The grafting yield was increased with increasing AA and BP concentration up to limiting value and then decreased. The grafting yield increased with reaction time up to 90 min. and then levelled off. The grafting rate was increased with increasing the reaction temperature up to 6$0^{circ}C$ but above that temperature decreased. The crystallinity of grafted film, evaluated from the result of DSC, was generally decreased with increasing grafting yield. The mechanical properties of grafted samples were also examined by the tensile tester. It has been found that the contact angle was decreased and the moisture regain and the degree of swelling were increased with increasing the grafting yield.