Some patients initially suspected of having Hunter syndrome may have multiple sulfatase deficiency in which deficiency of iduronate sulfatase dominates. Burk et al. (1981, 1984) reported 2 cases that had been mistakenly diagnosed as Hunter syndrome. In both, developmental delay dated from birth. Increased urinary mucopolysaccharides had a pattern different from that in mucopolysaccharidosis (heparan sulfate 39%, dermatan sulfate 21%, chondroitin sulfate C 40%). Abnormally broad great toes were found in both, and ichthyosis developed at an early age. Limitation in extension at the elbows and radiologic changes of dysostosis multiplex were suggestive of a mucopolysaccharidosis. The defect in this disorder may be similar to that in combined beta-galactosidase/neuraminidase deficiency; the defect may reside in a molecule necessary to protect the multiple sulfatases against excessive intralysosomal degradation and to assure their full hydrolytic capacity. If this is the explanation, then the activity of the molecule must not be limited to the intralysosomal site: 6 of the enzymes are lysosomal, whereas steroid sulfatase is microsomal.