The incidence, etiology, severity and mortality of acute pancreatitis in Denmark were investigated by examining published material from Denmark from the period 1979-1992 and information from the central registry of diagnoses from the period 1981-1990. The incidence of acute pancreatitis increased from 26.8 to 35.4 per 100,000 inhabitants per year from 1981 to 1990. An increase in the incidence among males was solely responsible for this total increase in incidence. Acute pancreatitis is significantly more frequent in men than in women, in men the frequencies in the age-group 15-64 and the age-group > 65 were the same. In contrast, acute pancreatitis was nearly twice as common among women of 65 or older as it was among the 15-64 year-old women. Oedematous pancreatitis accounted for 95% of the total number of cases registered, with minimal yearly variations (94.0-96.0%). The total mortality was low, with no systematic variation in the period studied (3.2%, yearly variations between 2.6 and 4.2%). Hospitalization time decreased over the period from an average of 12.8 to nine days.