The excretion of individual urinary 17-ketosteroids, pregnanediol and pregnanetriol, as measured in 98 healthy adults subdivided into groups according to age and sex, by means of a gas chromatographic analysis method based on enzymatic hydrolysis, extraction with ethyl ether, and conversion of the extracted steroids into trimethylsilyl ethers. The results showed that age and sex substantially influence the steroid pattern. Metabolites with 5-alpha configuration are predominant in young subjects; those with 5-beta configuration are pre-eminent in the more advanced ages, particularly in women. Metabolites with definite androgenous significance (C19O2-17KS) decline rapidly with advancing age, while the C19O3-17KS undergo a lesser decrease.