A preliminary report on the use of microtechniques for the detection of three lysosomal storage diseases (Tay-Sachs, GM1-gangliosidosis and Fabry disease) is presented. This microassay method uses from 100 to 300 cultured amniotic fluid cells or skin fibroblasts. A comparison between values for total activity and heat inactivated forms of hexosaminidase (in Tay-Sachs disease) is presented. The feasibility of the use of this microtechnique in prenatal diagnosis is discussed.