Enzyme histochemical procedures for both hydrolase and oxidoreductase enzyme activity were applied to cryostat sections of polyglactin 910 suture implant sites. Sutures were implanted either solely in tissue or in a combination of in vitro incubation followed by implantation in vivo for total time periods of seven to 56 days. Suture absorption rates were also measured. It is concluded from the results that neither cellular nor enzyme activity is necessary for the degradation and absorption of polyglactin 910 sutures. This conclusion is based on similar absorption rates for sutures implanted solely in vivo and sutures treated in vitro and then implanted in tissue to give equivalent time spans. There were strong indications, however, that the products of suture hydrolysis are probably metabolized through the oxidative enzyme systems of cells adjacent to the suture. This mechanism of polyglactin 910 suture absorption is quite different from that observed and reported for catgut absorbable sutures.