Glycosaminoglycan content, composition and molecular weight were determined in liver obtained from a patient with Morquio syndrome (Mucopolysaccharidosis IV). There was about a four-fold increase in glycosaminoglycan content (as hexosamine) of the affected liver as compared to the control liver. The major glycosaminoglycan accumulated in the liver was keratan sulfate, which was not found in the control liver. Chondroitin sulfates, especially chondroitin 6-sulfate, were also increased. Heparan sulfate isolated from the liver of a patient with Morquio syndrome was structurally different to that from control liver, and the glycosaminoglycans from Morquio syndrome were of a much lower molecular weight than those from control.