Peyronie's disease is an inflammatory disorder with no confirmed etiology. We have documented the familial transmission of the disease as an autosomal dominant trait in 3 pedigrees. The occurrence of Dupuytren's contracture in 7 of 9 (78 per cent) affected individuals, which is a significant increase over the average 0 per cent reported in sporadic cases, suggests that both of these fibrosing disorders are pleiotropic effects of the same gene in these families. Similarly, the histocompatibility B7 cross-reacting antigens were present in 90 per cent of the patients with Peyronie's disease. Additional studies, including careful family histories and histocompatibility antigen typing, are necessary to elucidate the role of histocompatibility antigens as a relative risk factor.