In a short-term (14 days) and a long-term (84 days) experiment after pancreatic duct occlusion in the rat, we measured the insulin, glucagon and somatostatin content of the pancreas; in the short-term experiment, in addition, we performed an oral glucose tolerance test on the 14th day. Exocrine pancreatic function in the short-term study was monitored on the 9th day – in the long-term study on the 21 st day. In the long-term study, the pancreatic organ was also examined histologically. Occlusion of the pancreatic duct considerably reduces exocrine function. This accords with the histologically observed atrophy of the exocrine parenchyma, above all in the body and tail (after 84 days). 14 days after occlusion, basal plasma glucose and insulin was about the same as in the sham-operated rats. Incremental insulin after the glucose load in occluded rats was delayed for about 30 min, but the pattern of plasma glucose was only insignificantly altered as compared with the sham-operated controls. The insulin content of the pancreas on days 14 and 84 after occlusion was increased, glucagon and somatostatin unchanged. We conclude, that (a) intraductal occlusion of the pancreas is a suitable tool for inducing an atrophy of the exocrine pancreas; (b) in the short-term, after the duct occlusion, oral glucose tolerance is preserved, but the passage of insulin into the blood is delayed and is associated with a high level of insulin in the pancreas; the cause or causes of this coincidence is/are unknow