Abstract The excretion of 5α- and 5β-reduced 11-deoxy and 11-oxy-17-keto-steroids, and 17-ketogenic steroids in the urine of 9 normal and 13 essential hypertensive females has been investigated by gas liquid chromatography. A significant reduction in the excretion of a 5β-reduced 11-deoxy-17-ketosteroid by essential hypertensives was confirmed. The proportions of 5β-reduced metabolites of 11-oxy-17-ketosteroids were not altered by hypertension, whereas they were significantly increased in the 17-ketogenic fraction. Similar amounts of 5α-reduced metabolites of 11-deoxy-17-ketosteroids were excreted by both groups, and greater amounts of 11-oxy-17-ketosteroids and 17-ketogenic steroids by the hypertensive group. The differences in Δ 4-5 α-and Δ 4-5 β-reductase activity, inferred from the proportions of metabolites excreted, may be the result of a differential effect of the elevated blood pressure on substrate specific Δ 4-5-reductases.