The aim of this study was to document the natural history of chronic hereditary pancreatitis and to compare its evolution to that of chronic alcoholic pancreatitis. Twelve subjects with chronic hereditary pancreatitis were followed up for a mean duration of 15.8 years (range, 1-23) and compared to subjects with chronic alcoholic pancreatitis who were followed up from 1972 to 1980. The subjects with chronic hereditary pancreatitis, when compared to those with chronic alcoholic pancreatitis, were found to have an earlier onset of symptoms (10.5 vs. 46.0 years, p < 0.05); a significant delay in diagnosis (14.3 vs. 3 years); a similar prevalence of pancreatic calcification (58 vs. 57%); a similar amount of pancreatic insufficiency; both endocrine (50 vs. 70%) and exocrine 42 vs. 38%); and a higher prevalence of pseudocysts (33 vs. 10%, p < 0.05). Only one pancreatic adenocarcinoma was diagnosed in a patient with chronic alcoholic pancreatitis. Apart from the earlier onset and the delay in diagnosis, chronic hereditary pancreatitis has a natural history similar to that of chronic alcoholic pancreatitis. The disease is progressive with a high incidence of complications, but all subjects were alive after follow-up.