We identified 35 homozygotes for hemochromatosis through pedigree studies. Thirteen were asymptomatic. Arthropathy was present in 20, hepatomegaly in 19, transaminasemia in 16, skin pigmentation in 15, splenomegaly in 14, cirrhosis in 14, hypogonadism in six, and diabetes in two. No homozygote was in congestive failure. Only one had the triad of hepatomegaly, hyperpigmentation, and diabetes. Serum iron was increased in 30 of 35, transferrin saturation was increased in all 35, serum ferritin in 23 of 32, urinary iron excretion after deferoxamine in 28 of 33, hepatic parenchymal cell stainable iron in 32 of 33, and hepatic iron in 27 of 27. Iron loading was 2.7 times greater in men than in women. No female had hepatic cirrhosis. Diagnosis of asymptomatic hemochromatosis is important because organ damage may be prevented by early therapy. Clinical diagnosis of early hemochromatosis is difficult. Persons with unexplained elevation of transferrin saturation should be studied for hemochromatosis.