Locus differentiation of hereditary mucopolysaccharidoses (MPS) was carried out using the methods of enzymodiagnosis and metabolic cooperation. MPS loci were differentiated in 66 patients from 58 families, examined in the Centre of Medical Genetics, as well as in 21 patient from 12 families, found in Uzbek and Turkmen populations. The following MPS types were detected: MPS I H, MPS I H/Sh, MPS II, MPS III A and B, MPSIV A and B, MPS VI. Among the patients examined MPC II was the most widespread type of the disease. Ethnic dissimilarity was noted in the MPS distribution over the USSR regions.