Thirteen patients with idiopathic hemochromatosis and their relatives were studied with regard to environmental and genetic factors in the development of the disease. Cooking utensils, iron medications or "tonics," and blood transfusions were not contributory causes. There was excess alcohol intake in 54% (seven) of the patients, but the average amount of iron absorbed was approximately 2.61 gm, which is much lower than the 20.41 gm found in the organs in other patients with hemochromatosis.4 The mean serum iron and plasma transferrin saturations were higher in the male and female relatives than in normal controls and nonblood relatives. Environmental factors were not the cause of this difference. The familial clustering of cases and high serum iron values indicate a genetic etiology, but the pattern of transmission is not clear. Alcohol and other environmental factors were not absolutely necessary for the development of the syndrome.