Nearly one hundred families affected with hereditary chronic pancreatitis (HCP) have been reported in the literature. However, the fact that the disease involved only a few members of each family limits the informativeness of these reports and accounts for the infrequency and disappointing results of pathogenetic and genetic research. Our study concerned an exceptional HCP genealogy which would seem to provide an ideal model for the detection of a genetic anomaly linked to the expression of the disease. We studied 249 members of a family (214 still alive), covering eight generations born between 1800 and 1993. According to the customary criteria, 63 had definite and 17 probable HCP. Fifty-eight members under 18 years of age were still susceptible to developing the disease. This series confirms the mode of autosomal dominant heredity with variable penetrance. The clinical features and disease course were typical, except that symptoms tended to appear earlier. The series represents the most extensive HCP genealogy compiled and is one of the largest families studied in the field of genetic disease, regardless of etiology. Blood samples were taken from 146 subjects to facilitate pathogenetic and genetic research.