A 36-year-old woman who had experienced two pregnancies consulted our hospital, because of scant menses and virilization. A 24-hour excretion of 17-ketosteroids and 17-hydroxy-corticosteroids demonstrated a decrease in 11-hydroxylase. A computed tomogram showed a huge inhomogenous tumefaction in the left adrenal. Left selective renal angiography revealed a large adrenal tumefaction. Selective adrenal venous samplings revealed that testosterone and dehydroepiandrosterone (DHA) were produced in response to stimulation by 0.25 mg exogenous adrenocorticotropic hormone (ACTH). After left adrenalectomy was performed, a diagnosis of adrenocortical carcinoma was made by pathological examination. This is the first report of a patient with a virilizing adrenocortical carcinoma, which produced testosterone and DHA in response to exogenous ACTH stimulation.