A special programme for the diagnosis and prevention of lysosomal storage diseases (LSD) was developed in the former USSR. All the patients from 814 families at risk were investigated using biochemical techniques. In total, 363 patients with mucopolysaccharidoses (MPS), mucolipidoses, glycoproteinoses, sphingolipidoses and other LSD were diagnosed; 55 families at risk sought prenatal diagnosis and 67 fetuses were investigated for MPS (types I, II, IIIA and IIIB, VI), Tay-Sachs disease, Sandhoff disease, GM1-gangliosidosis, metachromatic leukodystrophy, mannosidosis, Gaucher disease and multiple sulphatidosis; 17 affected fetuses were diagnosed and aborted. There was an ethnic distribution of different lysosomal storage diseases in the former USSR.