There is increasing interest in pancreatic transplantation for patients with diabetes. In experimental models, endocrine function is usually monitored by determination of insulin and glucose levels in plasma. In this study following a segmental pancreatic autotransplant to the iliac fossa in dogs, a combined analysis of three pancreatic islet hormones, insulin, pancreatic polypeptide (PP) and glucagon was undertaken by radioimmunoassay of plasma. These were measured under basal conditions and following provocation with a standard meal, arginine, secretin and bombesin infusions. Immunohistochemical and electron microscopic examination of transplanted tissue was also performed. Circulating insulin and glucose levels in the surviving dogs with transplants reflected normoglycaemia with a normal tolerance to iv glucose and immunohistochemical detection of endocrine cells producing insulin, PP and glucagon. Secretory granules were found in A and B cells by electron microscopy. The normal circulating glucagon immunoreactivity could have originated in gastric antral A cells as well as in pancreatic tissue. It was not possible, however, to stimulate the autotransplanted pancreas to release detectable PP into the circulation.