Most of 147 acute pancreatitis patients had abdominal pain and tenderness corresponding to the location of the pain. Temperature was rarely over 101 F (38.3 C) and in many patients was normal. In some patients with obscure abdominal pain and normal serum amylase levels, elevation of the serum lipase or urinary amylase levels helped to establish the diagnosis of acute pancreatitis. In 53% of the patients, alcoholism was an important etiologic factor, in 22% no etiologic factor could be found, and in the remainder several associated etiologic factors were present. Anticholinergic drugs appeared to reduce the complication rate; antibiotics caused no significant improvement in the incidence of complications. Mortality was 23%. Forty-three percent of deaths were due to shock, the remainder to a variety of causes.