Macroporous particles, prepared by the suspension polymerization of ethylene dimethacrylate (EDMA), possessing high specific surface areas (558 m2 g-1) and pore volumes (6.9 ml g-1), contain unreacted double bonds which are accessible for free radical polymerization. The amount of unreacted double bonds was determined by C-13 CP/MAS n.m.r. These bonds were used for the functionalization of poly(EDMA) particles by the solution grafting copolymerization of glycidyl methacrylate (GMA) into the pore structure of the particles. The poly(GMA) formed in this way is permanently attached to the particles. By this method composite particles, containing up to 77 wt% of oxirane groups (determined by i.r. spectroscopy), were obtained. However, the presence of grafted polymer in the pores leads to a decrease in both the pore volume and the specific surface area. The oxirane groups can be chemically modified, as evidenced by their reactions with hydrogen chloride and 2,2,6,6-tetramethyl-4-aminopiperidine.