A review of acute pancreatitis occurring over a 20-year period in the Bristol clinical area is reported. A total of 590 cases were available for analysis. The yearly incidence was 53-8 per million population at risk, with a mortality of 9-0 per million. This compares favourably with 11-4 deaths per million for England and Wales as a whole during the same period but the difference is not statistically significant. When the deaths occurring in the Bristol clinical area were expressed in terms of case mortality rate the figure was 17%. In contrast the mortality for recurrent acute pancreatitis was only 1-5%, and the benign nature of this second condition is confirmed. Aetiological factors and age and sex distribution were also analysed in relation to each other and to mortality. An increase in acute pancreatitis secondary to chronic alcoholism was confirmed and steroid pancreatitis also emerged as a definite entity in this survey. The pattern of recurrence in patients with idiopathic pancreatitis was studied in detail and is analysed on an actuarial basis.