The MPSs are a heterogeneous group of disorders caused by the deficiency of one of ten lysosomal enzymes and the resultant accumulation of glycosaminoglycans in tissues and organs. The phenotypic variations of each disorder are continuing to be expanded, while the biochemical explanation of these variations needs to be defined. Mucopolysaccharidoses should not be diagnosed solely on clinical grounds, since laboratory confirmation by specific enzyme assay in now available. Prenatal diagnosis is possible for MPSs by amniocentesis. Chorionic villus sampling offers the possibility of first trimester diagnosis. Carrier detection in Hunter's syndrome is not routinely performed, but new procedures may make this needed service more available. No definitive treatment is available. Bone marrow transplantation appears to improve the somatic disease, but correction of the central nervous system disorder may not be possible. The successful development of gene-therapy may in the future provide a means of treatment in MPSs. The management of MPSs can be improved by a better understanding of the natural history of the somatic and central nervous system deterioration in the different disorders. Systematic evaluation and appropriate treatment can lead to an improved quality of life.