To clarify a possible cause of hyperamylasemia in end-stage renal disease (ESRD), histological studies were performed on the pancreatic glands of twenty-seven autopsied patients with ESRD who had received long-term hemodialysis. The findings were compared with those in a similar number of age-matched control subjects. Histological evidence of pancreatitis was found in 51.9% of the ESRD patients as compared with 14.8% in the controls (p < 0.005). The pancreatitis was chronic in nature in 85.7% of the ESRD patients showing changes of pancreatitis. Secretin administration to an additional group of twelve patients with ESRD induced an elevation in the activities of both total and P-type serum amylase in only one patient. These findings suggest that although histological pancreatic alterations are common in patients with ESRD, they are probably not responsible for the P-type hyperamylasemia frequently found in such patients.