Forty-five women with hirsutism were compared with 16 normal women as to various clinical features and laboratory findings, particularly the 24-hour urinary output of 11 desoxy, 11-oxygenated, and total neutral 17-ketosteroids. In seven of the patients the hirsutism was part of a surgically verified Stein-Leventhal syndrome; in 22 it was associated with irregularities of menstruation. There were also 16 patients in whom the hirsutism, generally less severe than in the others, coexisted with regular menstrual rhythm. Prednisone, in daily doses of 7.5 to 15 mg., reduced total neutral 17-ketosteroid excretion to normal in all patients and gave fair to good improvement as to hirsutism in all patients treated with it. Amenorrhea, oligomenorrhea, and menometrorrhagia responded remarkably to prednisone. The clinical results were gratifying. Physiologically they strengthen the belief that in hirsutism of this type the ovarian changes are secondary to primary changes in the adrenals.