109 women with hirsutism were investigated (102 with idiopathic hirsutism, four with Stein-Leventhal syndrome, one each with adrenal adenoma, adrenal carcinoma and hilus-cell tumour). Levels of testosterone, dihydrotestosterone, androstenediol and dehydroepiandrosterone were measured, usually in the course of a combined adrenal-ovarian stimulation-suppression test. Measuring several plasma androgens made it possible to distinguish idiopathic hirsutism from other endocrine diseases with hirsutism. Mean plasma testosterone level in idiopathic hirsutism was not significantly different from that in healthy women. Elevated testosterone and(or) dihydrotestosterone levels were found in only 22 of 102 women. There was a marked increase in plasma testosterone after HCG injection in the patient with Stein-Leventhal syndrome. Androstenediol and dehydroepiandrosterone were both important in the diagnosis of autonomous adrenal steroid secretion.