The incidence, etiology, clinical characteristics, and long-term outcome of patients with chronic pancreatitis (CP) studied at the Instituto Nacional de la Nutrición in a 12-year period were retrospectively analyzed. One hundred fifty cases were identified, with an overall incidence of 4.4 per 1,000 hospital admissions and of 5.4 per 1,000 in the last 6 years. In 68% of the cases, CP was secondary to alcoholism, in 29% it was idiopathic, and in the rest it was secondary to other causes. Overall, 74% of patients had pancreatic calcifications at time diagnosis was established, and 21% were asymptomatic regarding pain. Patients with idiopathic CP had an earlier age of onset than did patients with alcoholic CP, and in addition the former developed symptoms of diabetes or pancreatic exocrine insufficiency less frequently than alcoholic patients did (p less than 0.05). The sex ratio was different in both groups, with a marked male predominance in alcoholic CP and an equal distribution in the idiopathic group. A 30% actuarial mortality was found in the first 10 years after the onset of the disease, which remained the same at 20 years with a tendency to better survival in nonalcoholic patients. Five patients developed pancreatic cancer throughout the study period.