A sibship is reported in which four brothers died of adenocarcinoma of the pancreas in the seventh or eighth decade of life. None of the patients had a history of pancreatitis, other malignant neoplasms, or exposure to a known pancreatic carcinogen. This family seems to exhibit a genetic predisposition to pancreatic carcinoma late in life, but the mode of inheritance and the relative importance of genetic and environmental factors in the development of these tumors are unclear.