Polarizing material has been reported in the liver of children with infantile Refsum's disease (IRD) and was absent in two patients with the cerebro-hepato-renal syndrome of Zellweger (CHRS). We examined in polarized light 15 liver biopsy and autopsy samples from six other patients with the cerebro-hepato-renal syndrome of Zellweger, two with the rhizomelic form of chondrodysplasia punctata (rCDP) and two with X-linked adrenoleukodystrophy (ALD), all conditions with deficient peroxisomes. Two types of birefringent inclusions were found in CHRS only: the first is transparent in bright field, the second appears as brown granules or rods, similar to lipofuscins. As in IRD large PAS-positive macrophage-like cells contain the transparent type. Electron microscopical investigation of these cells shows trilaminar structures within membrane-bound organelles. The two types were also seen in kidney and brown adipose tissue, the first type in pancreas, the second type in adrenal gland; no such was observed in myocardium or in thyroid gland (CHRS). No birefringent inclusions were present in rCDP and ALD. The nature of the inclusions is still unclear. An accumulation of the transparent polarizing material with increasing age of the patients is most likely.