Photoinitiated grafting is an excellent method to modify the surface properties of a polymer. The presoaking photografting method applied to poly(ethylene terephthalate) (PET) with acrylic acid or acrylamide as monomer using benzophenone as photoinitiator has been investigated. The photografting proceeds under nitrogen atmosphere in a continuous process. The relative intensity of the ESCA lines of nitrogen over carbon of the fiber grafted with acrylamide increased from 3–4% (background) to 8% for 20-s irradiation time. Measured by titration, the amount of grafted poly(acrylic acid) is 0.821 and 1.528 mg/m2 with 0.5 M and 2.0 M acrylic acid concentration, respectively, in the presoaking solution at 10-s irradiation time. The dyeability of the fiber, measured by UV absorption, improved. The concentration of initiator and monomer and the solvent used affected the grafting yield. Appropriate conditions promoted photografting of the poly(ethylene terephthalate) fiber. Acetone was a somewhat better solvent than methylethylketone and methylpropylketone.