A series of 10 patients with benign androgen-secreting neoplasms is presented. Nine tumors were ovarian, and one adrenal. In an attempt to correctly diagnose the presence of tumor and to accurately localize the lesion to a specific gland, steroid hormones in peripheral, ovarian, and adrenal vein serum were analyzed by radioimmunoassay. Little correlation was made in this series with those levels of testosterone (greater than 2 ng/ml) or dehydroepiandrosterone sulfate (greater than 7000 ng/ml) that have been widely used to predict the presence of such tumors. Peripheral testosterone levels were less than 2 ng/ml in 50% of our patients, and the dehydroepiandrosterone sulfate level was greater than 7000 ng/ml in only a single patient with an ovarian lipoid cell tumor. Pelvic ultrasonography was found to be of limited value in evaluating nonpalpable tumor because of the small size (less than 2 cm3) of the majority of these neoplasms. The use of selective retrograde venous catheterization to demonstrate significant effluent-peripheral vein androgen gradients served to accurately localize androgen-secreting tumors in all six patients in which it was used. Our data emphasize the potential pitfalls that exist in the preoperative evaluation of patients with these fascinating neoplasms and the importance of a high degree of suspicion on the part of the physician caring for these women.