The regulatory mechanisms governing aldosterone secretion in man are as yet obscure. Axelrad and Leutscher 1 have shown that a fivefold increase in urinary aldosterone occurs in man when the dietary sodium is restricted. Laragh and Stoerk2 have suggested that serum potassium is a powerful direct or indirect stimulus to aldosterone secretion and that increases in urinary aldosterone on dietary sodium restriction are mediated by an alteration in serum potassium or Na/K ratio. Although corticotropin does not appear to affect either the excretion * or the blood levels of aldosterone in normal persons,4 Gordon and co-workers 5 have found an increase in the output of this sodiumretaining hormone in a patient with rheumatoid arthritis following the intravenous administration of corticotropin. Leutscher and Axelrad 6 have observed essentially normal levels of urinary aldosterone in patients with panhypopituitarism. It has been sug- gested by Peters 7 that the mineralocorticoid output of