The Bardet-Biedl syndrome is a rare autosomal recessive disorder characterized by pigmentary retinopathy, obesity, polydactyly, hypogonadism, and mental retardation. Renal abnormalities, hypertension, acquired heart disease, and hepatic fibrosis also occur in homozygotes. Two adult Bardet-Biedl sibs, a man with hypertension and cardiomegaly and a woman with biliary cirrhosis, and 75 relatives in 5 generations of the extended family were identified. Hospital records for major illnesses, death certificates, and autopsy reports were examined. The frequent observation of obesity, hypertension, diabetes mellitus, and renal disease in first-degree relatives, obligate gene carriers, and other blood relatives raise the possibility that Bardet-Biedl heterozygotes are also predisposed to these disorders.