Introduction: Virilization in a postmenopausal woman requires evaluation for an androgen-secreting tumor. The differential diagnosis includes adrenal carcinomas and adenomas and Sertoli-Leydig cell tumors, granulosa-theca cell tumors, and hilus-cell tumors of the ovaries. We present a case of virilization in a postmenopausal woman caused by a Sertoli-Leydig cell tumor (SLCT) in which evaluation was complicated by the pattern of androgen elevation, bilateral adrenal nodules, and absence of an adnexal mass. Case: A 64-year-old female was referred for evaluation of hyperandrogenism. Hirsutism, temporal hairline regression, and unusually deep voice were noted on examination. Two total testosterone levels obtained one month apart were 146 ng/dL (2-45), and measurements of dehydroepiandrosterone sulfate (DHEAS) and androstenedione were 299 mcg/dL (12-133) and 1.84 ng/mL (0.130-0.820), respectively. Abdominal CT revealed bilateral adrenal nodules - 2 cm and - 5 Hounsfield units (HU) on the left, and 1.5 cm and 5 HU on the right - but no ovarian masses. Transvaginal ultrasonography also failed to identify a discrete ovarian mass but showed endometrial hyperplasia. Virilization, magnitude of testosterone elevation, and results of imaging were felt to be most strongly indicative of ovarian hyperthecosis, and the patient underwent laparoscopic bilateral salpingo-oophorectomy and hysterectomy. The right ovary was 2.3 cm in largest diameter and approximately 90% replaced by an orange-red mass that showed Sertoli and Leydig cells on microscopy, immunohistochemical staining for the sex cord proteins inhibin and calretinin, and presence of the Leydig cell marker melan A. It was classified as well differentiated. Additional CT imaging and robotic assisted laparoscopy confirmed a stage IA tumor. One month after surgery, hyperandrogenemia had completely resolved (total testosterone < 10 ng/dL, androstenedione 0.379 ng/mL, and DHEAS 99 mcg/dL), and changes of virilization had mostly regressed at an eight months appointment. Discussion: SLCTs are a type of sex-cord stromal ovarian tumor. They constitute < 0.5% of ovarian tumors but account for approximately 75% of testosterone-secreting ovarian masses. This patient’s case was unusual for multiple reasons: 1. Age - most SLCTs are diagnosed in the second or third decade, 2. Imaging - CT and ultrasonography usually show a solid or solid and cystic adnexal mass, and co-existing adrenal nodules are rare, likely due to typical young age of presentation, and 3. Pattern of androgen elevation - DHEAS was more than two-fold elevated, and usually < 10% of DHEA and DHEAS are produced by the ovaries. However, DHEAS fell significantly after oophorectomy. SLCTs are a potential etiology of virilization in postmenopausal women even in the absence of a detectable adnexal mass and when biochemistries and imaging raise the possibility of an adrenal source of androgen.