A standard method for bovine islet isolation has been developed. The mean islet yield per gram pancreas obtained from the last twelve consecutive glands was 2,098 +/- 292 representing an insulin recovery of 36.1 +/- 6.5%. The static incubation of freshly isolated bovine islets in the presence of glucose resulted in a less distinct increase of insulin secretion than in the presence of free fatty acids. Nevertheless, xenotransplantation of bovine islets to immunosuppressed C57BL6J mice did reverse streptozotocin-induced diabetes for 2 to 6 days.