We compared hepatic morphology, hepatocellular siderosis, extrahepatic parenchymal siderosis, and (by chemical assay of liver and spleen) the amount of elemental iron and copper in 12 cases of perinatal hemochromatosis (PH) with 119 perinatal controls. Controls were subgrouped according to diagnoses based on clinical and autopsy findings; 37 had chronic liver disease, either hepatic fibrosis (17) or cirrhosis (20). Graded semiquantitatively, hepatocellular siderosis varied widely among controls, and some showed more than PH cases. By chemical assay, total hepatic iron in PH cases was not significantly greater than in any control group except the preterm. Therefore, our findings do not support an etiological role for iron in PH. Its distinctive hepatic morphology seems related to onset of liver disease during fetal life, when periportal hepatocytes normally contain hemosiderin (as in 71 of 82 controls without chronic liver disease). Environmental agents (such as hypoxia, virus, drug) that could damage a fetal liver would usually damage other fetal organs as well. They would be unlikely to recur in a subsequent pregnancy and thereby account for PH occurring in siblings. In initiating PH, therefore, putative environmental agents may need to interact with a factor or factors intrinsic to the developing fetal liver.