Peyronie's disease, a connective tissue disorder of unknown cause, is characterized by the formation of thickened fibrous plaques on the dorsum of the penis. It often occurs simultaneously with other fibrotic changes, most notably Dupuytren's contracture of the hands or feet. There are no previous reports suggesting inheritance of this syndrome; however, Willscher et al reported an association between Peyronie's disease and antigens of the HLA-B7 cross-reacting group. Family studies were undertaken when three patients reported similarly affected first-degree relatives. One kindred showed father-to-son transmission of Peyronie's disease with Dupuytren's contracture in three generations. Pedigree analysis of the three families suggests that Peyronie's syndrome is a male-limited, autosomal-dominant trait. Antigens of the HLA-B7 cross-reacting group occurred in all three kindreds; however, the data ruled out close linkage of the disease and HLA.