Synthetic dehydroepiandrosterone sodium sulfate underwent hydrolysis when subjected to ethyl acetate or tetrahydrofurane containing perchloric acid. In agreement with Burstein and co-workers, this type of hydrolysis will also cleave 17-ketosteroid glucuronosides. The perchloric acid-ethyl acetate hydrolysis has been applied to human urine, and with 3-hr incubation at room temperature the degree of hydrolysis of conjugated urinary 17-ketosteroids was at least that which could be achieved by hot acid hydrolysis. Gas-liquid chromatography of the 17-ketosteroids after hot acid hydrolysis indicated some destruction; in particular, dehydroepiandrosterone was unstable. Ethyl acetate-perchloric acid hydrolysis did not produce such destruction. The data obtained indicate that the following hydrolytic procedures are adequate when working with conjugated urinary 17-ketosteroids: a) β-glucuronidase for 17-ketosteroid glucuronosides; b) ethyl acetate-sulfuric acid solvolysis for 17-ketosteroid sulfates; c) ethyl acetate-perchloric acid solvolysis for 17-ketosteroid glucuronosides and sulfates.