Deficiency in the lysosomal enzyme responsible for cholesteryl ester hydrolysis, acid cholesteryl ester hydrolase (E.C. 3.1.1.13), leads to two clinically recognized diseases: Wolman disease and cholesteryl ester storage including leukocytes, fibroblasts and liver. Analysis of urinary sediment from well characterized cases of Wolman disease and CESD also revealed the shedding of lipid enriched renal tubular cells. Morphologic, enzymic and lipid compositional studies of these cells indicate that the enzyme deficiency observed in fibroblasts and leukocytes from these individuals are reflected in these cells shed in the urine. These findings in renal tubular cells confirm and extend those made in other cell types. These studies indicate that analysis of urinary sediment in suspected cases of acid cholesteryl ester deficiency may provide a meaningful approach for monitoring therapeutic attempts involving enzyme infusion and gene therapy.