The low frequency rheological behaviour of a family of glycidyl methacrylate and styrene graft modified polypropylenes was studied. Two initiators were examined in the grafting process and were found to produce significantly different copolymers in terms of the degree of grafting, molecular weight, and rheological properties. Rheological evidence that p-scission occurred during the grafting process was found for the PP-g-GMA copolymers. A slight increase in the elastic response was observed for the samples prepared using L 231, most likely due to crosslinking via epoxy ring opening. The elastic response of the styrene grafted copolymers was enhanced significantly, and the copolymers behaved like typical crosslinked materials at higher levels of grafted styrene. The low frequency storage modulus (G’) increased, spanning more than 2 decades, with the addition of styrene as a comonomer for the grafting of GMA. At higher levels of grafting, both the PP-g-S and PP-g-(GMA-S) copolymers were sufficiently crosslinked that G’ was greater than G ", the loss modulus, over the entire frequency range examined. However, these samples contained no gel material as determined by Soxhlet extraction with xylene.