The connective tissues of diabetic humans and experimental animals exhibit abnormalities in collagen metabolism including an increased production of collagenolytic enzymes by gingival explants in tissue culture. In the current study, gingival tissue and skin were obtained from control and diabetic rats, the latter on the 5th, 10th, 15th, and 22nd day after inducing the disease with streptozotocin. Extracts of the tissues were assessed for collagenase activity using either14C‐labeled collagen fibrils or Peptide‐P as substrate and by detecting collagenase digestion products by SDS‐polyacrylamide gel electrophoresis. Elastase was measured using the specific substrate, succinyl‐(L‐Alanyl)3‐p‐nitroanilide. Diabetes increased the activity of collagenase in extracts of gingiva and skin; elastase, however, was increased dramatically only in the latter tissue. These findings (1) indicate that diabetes‐induced enhanced gingival collagenase activity occursin vivoas well asin vitroand (2) explain, at least in part, the greater loss of collagen in skin than in gingiva of the diabetic rat and other complications such as unusually severe period