1. Using a newly developed and validated radio-assay method, we have measured plasma 11-deoxycorticosterone concentrations in a wide spectrum of human hypertensive states.
2. Patients with essential and renovascular hypertension have normal plasma concentrations of 11-deoxycorticosterone.
3. Elevated concentrations are seen in some patients with primary aldosteronism, Cushing's syndrome, low-renin hypertension, and in adult hypertensive subjects with elevated urinary 17-ketosteroid excretion.
4. An aetiological role for deoxycorticosterone in certain forms of human hypertension appears likely.