Polypropylene (PP) film was plasma-treated using a 13.56 MHz direct plasma with argon, nitrogen, and oxygen as the plasma-forming gases. The three gases induced very different changes on the PP film surface, which were studied using contact angle measurements. Because of its degrading and oxidative effect, oxygen plasma pretreatment was not used for the homogeneous grafting of acrylic acid and acrylamide. Nitrogen plasma treatment did not lead to the formation of stable peroxides on the film surface and did not undergo grafting reactions. This may be due to the types of radicals and functional groups created on the surface during the plasma treatment. Finally, argon plasma pretreatment was found to be the most effective for the grafting of vinyl monomers. The amount of grafted poly(acrylic acid) was shown to be proportional to the concentration of peroxides created by argon plasma treatment.