Twenty-two hirsute women underwent percutaneous adrenal and ovarian vein catheterization to differentiate and localize excessive hormonal output. All studies were done under fluoroscopic control; catheter placement was verified by venography, and blood samples were withdrawn for hormonal analysis. The right ovarian vein was successfully sampled in 42 per cent of attempts; the left ovarian vein, in 75 per cent; the right adrenal vein, in 56 per cent; and the left adrenal vein, in 100 per cent. Bilateral catheterization did not prove clinically useful. First, anatomic variations in venous size and drainage made catheterization and bilateral sampling difficult. Second, adrenal secretion is both episodic and parallel, necessitating both simultaneous catheterization and serial sampling for adequate diagnosis. The stress of the procedure may provoke increased adrenal output. Third, since ovarian secretion is not parallel, and since increased hormone output has been documented in that ovary containing developing follicles or a corpus luteum, distinguishing ovarian dysfunction proved difficult. Finally, for a time-consuming procedure, patient discomfort cannot be disregarded. This technique has not proved to be a reliable means of determining the site of androgen hypersecretion and thus cannot be recommended in the routine evaluation of female hirsutism.