Acrylamide was graft polymerized onto the surface of a chemically crosslinked and amorphous biodegradable polyester, poly(1,5-dioxepan-2-one). Electron beam irradiation at a dose of 5 Mrad was used to generate the initiating species in the polyester. The degradation behavior in vitro at pH 7.4 and 37 degrees C in a phosphate buffer solution was studied for untreated, irradiated, and acrylamide-grafted polymer. Differences in weight loss performance were observed between virgin and treated polymers. The acrylamide-grafted poly(1,5-dioxepan-2-one) was totally degraded after 43 weeks as compared to 48 weeks for the irradiated and 55 weeks for the virgin polymer. On the other hand, the treated polymers showed a higher resistance to degradation in terms of weight loss during the intermediate part of the degradation, i.e., between about 5 and 35 weeks. After this period, the irradiated and particularly the acrylamide grafted poly(1,5-dioxepan-2-one) degraded much more rapidly than the virgin polymer.