Photoinduced graft copolymerization of acrylamide (AM) onto two types of acrylonitrile-butadiene-styrene (ABS) copolymers was extensively investigated in homogeneous media. The grafting process was conducted in chloroform in presence of 4-acetyldi-phenyl (4-AD). Ultraviolet (UV) irradiation was used in the range of 310 to 460 nm. The UV spectrum of 4-AD has sλmaxat 285 nm and shows n-π*transitions. The grafting parameters, such as weight conversion, grafting percentage, and grafting efficiency, were determined as a function of the irradiation time and the concentrations of monomer, initiator, and substrate. A reverse effect was observed between the grafting percentage and the butadiene content in ABS copolymers. The rates of graft copolymerization of AM onto the two types of ABS copolymers were determined. A Trommsdorf effect was observed in certain systems. The IR spectrum of ABS-g-AM graft copolymer shows the appearance of a new peak at 1685 cm-1that declares the presence of poly-acrylamide-grafted chains onto the ABS copolymer backbone. A probable copolymerization mechanism was proposed.