Four fetuses with positive family histories for cerebrohepatorenal (Zellweger) syndrome (CHRS) underwent diagnostic amniocentesis or chorionic villus biopsy. Cultured amniocytes or fibroblasts from all of the fetuses displayed abnormal fatty acid ratios, and the parents elected therapeutic abortions. Dysmorphic features in one fetus consisted of micrognathia, proximal implantation of toes, and bilateral talipes equinovarus. Radiologic examination of the fetus confirmed the dysmorphic features and revealed foci of mineralization in the patellae. Biochemical analysis of three of the fetuses demonstrated markedly increased levels of very-long-chain fatty acids, both saturated and monounsaturated, in liver, kidney, adrenal, and brain. Pathologic findings consisted of premature mineralization of patellae; renal cystic tubular dilations; striated cells in adrenal fetal zone and testicular interstitium; dysplastic alterations of inferior olivary nuclei, dentate nuclei, and cerebral cortex; equivocal increases in portal fibrous tissue; and abnormal cytosomes in fetal zone adrenocortical cells, testicular and renal interstitial cells, and brain macrophages. Iron deposition, probably physiologic, was observed only in liver tissue. Distributions of immunoreactive catalase were identical in the fetuses with CHRS and age-matched control subjects. These findings document the accuracy of the prenatal diagnostic test and provide insights into the morphogenesis and pathogenesis of CHRS.