The postmortem biochemical and pathological findings in the first patient reported with mucopolysaccharidosis VII are described. Clinical, radiographic, and biochemical features of this 19-yr-old black man were initially reported in 1973 when, at age 2 1/2 yr his enzymatic defect, deficiency of beta-glucuronidase, was identified. The autopsy findings are now described with biochemical data further characterizing the enzyme deficiency and resultant glycosaminoglycan accumulation. He had dysostosis multiplex and extensive cardiovascular lesions including arterial stenosis, and marked fibrous thickening of the atrioventricular and aortic valves. Microscopic evidence of lysosomal storage was found in bone, cartilage, arteries and cardiac valves, liver, spleen, lymph nodes, eyes, adrenal, pituitary, and the central nervous system. In the brain, storage was localized to specific regions, primarily intraneuronal, and appeared ultrastructurally as delicate whorled filamentous accumulations in lysosomes. Similar filamentous storage also occurred in medial cells of the aorta. Multiple postmortem tissues contained only trace amounts of beta-glucuronidase and elevated glycosaminoglycans, predominantly chondroitin 4- and 6-sulfate.