The cerebro-hepato-renal syndrome of Zellweger is an autosomal recessive inborn error of metabolism. Clinically the disease is characterised by craniofacial malformations, a lack of muscle tone, disturbances in liver function, renal cysts and mental retardation. The disease is characterised biochemically by the absence of peroxisomes (microbodies) in liver and kidney and variable abnormalities in mitochondria. This results in elevated concentrations of pipecolic acid and of tri(di)hydroxycoprostanoic acid in urine, CSF and/or duodenal fluid, an elevation of the concentration of very long chain (greater than C22) fatty acids in plasma and fibroblasts and a deficiency of plasmalogens in tissues, erythrocytes and fibroblasts. Moreover, we recently found that in Zellweger patients the activity of dihydroxyacetone phosphate acyltransferase is deficient in tissues, fibroblasts and cultured amniotic fluid cells and that the incorporation of a radioactive precursor of plasmalogens into phospholipids is impaired in fibroblasts and amniocytes. These recent findings allow specific prenatal and postnatal diagnosis of this disease.