Liver iron concentrations were determined in 60 alcoholics with liver disease of varying severity, 15 patients with untreated idiopathic hemochromatosis, and 16 control subjects with biliary tract disease. Mean liver iron concentrations (microgram/100 mg dry weight) were significantly greater in the alcoholics (156.4 +/- 7.8 (SEM); P less than 0.05) and in patients with idiopathic hemochromatosis (2094.5 +/- 230.7; P less than 0.01) than in control subjects (53.0 +/- 7.0). Liver iron concentrations of greater than 140 micrograms/100 were found in 17 alcoholics (29%) and in all 15 patients with idiopathic hemochromatosis. Liver iron concentrations greater than 1000 micrograms/100 mg were found in all patients with idiopathic hemochromatosis but in none of the alcoholics. In the alcoholics no relationship existed between liver iron concentrations and the amount of alcohol consumed daily, the length of the drinking history, the amount of beverage iron consumed daily, or the severity of the liver disease. Serum ferritin concentrations reflected iron stores in patients with hemochromatosis and in alcoholics with minimal liver disease. However, in alcoholics with significant liver disease serum ferritin concentrations did not reflect iron stores accurately, although with normal values iron overload is unlikely. Serum iron concentration and percentage saturation of total iron-binding capacity were of little value in assessing iron status in either alcoholics or patients with hemochromatosis. Measurement of the liver iron concentration clearly differentiates between alcoholics with significant siderosis and patients with idiopathic hemochromatosis.