The grafting of 2-(dimethylamino) ethyl methacrylate (DMAEMA) on to linear low-density polyethylene (LLDPE) using peroxide initiators was studied in an intermeshing co-rotating twin-screw extruder. The grafting reactions were carried out above the apparent ceiling temperature of the DMAEMA monomer. It was observed that above this ceiling temperature homopolymer propagation reactions are no longer occurring. The homopolymer initiation step was seen, however, to consume significant quantities of monomer, thus resulting in low grafting efficiencies (GE). Reducing the monomer concentration was shown to suppress the homopolymer initiation reaction and provide high grafting efficiencies with little loss in graft levels. It was also observed that initiator concentration controls the overall conversion and degree of grafting (DG) as well as crosslinking. Graft levels are therefore limited by the amount of crosslinking that can be tolerated in the final graft product.