The pancreatitis-associated protein (PAP) was investigated in patients with hereditary and chronic alcoholic pancreatitis. Blood levels of pancreatic enzymes and PAP were measured in nine families with hereditary pancreatitis; in three of them, the mutation N21I, and in six, the R117H variant of the cationic trypsinogen were present. In all family members, similar to controls, only normal values of the PAP were found. There was no evidence for polymorphism of the PAP gene in patients with hereditary or alcoholic pancreatitis. Immunohistochemically PAP was detected in the apical parts of the acinar cells but not in ducts, interstitial tissue, islets, or blood vessels. Intensity of PAP labeling was directly related to the deterioration of the acinar units, and its concentration was inversely related to chymotrypsinogen immunoreactivity in the same tissue. Similar immunohistochemical findings were present in chronic alcoholic and hereditary pancreatitis. We conclude that there is a lack of PAP polymorphism in hereditary and alcoholic pancreatitis and that expression of the PAP in both groups of patients is related to the degree of cellular damage of the pancreas.