Abstract Background Ovarian cystadenomas are classically considered as 'non-functional' tumors and among the most common benign ovarian neoplasms. Most of these tumors are asymptomatic and found incidentally on pelvic examination or with ultrasound. In rare circumstances these tumors may present as functional with secretions of excess androgens that subsequently produce virilizing features. Clinical Case A 59 year old Hispanic female G3P3(3003) presented to the clinic for receding hairline and facial hair for a duration of almost 2 years. Her medical history included total abdominal hysterectomy, due to fibroids, syphilis treated in Dominican Republic, Obesity, Vitamin D deficiency. On examination patient had hirsutism and significant hair growth on the abdomen, axilla, chest and extremities. The clitoris was enlarged, had frontal blading and increased abdominal circumference. Initial laboratory studies showed total testosterone was elevated [264 ng/mL] and free testosterone was high normal [4.2 pg/mL], DHEA-Sulfate normal [29.2 ug/mL], CA 125 unremarkable [5 U/mL]. Repeat labs were done showed elevated total testosterone and free testosterone [276 ng/mL and 4.7 pg/mL respectively] Normal levels of DHEA [87ng/dL] and DHEA-sulfate [ug/mL], 17-Hydroxyprogesterone [64 ng/mL], FSH normal [41.7 IU/L], LH normal [26.6 IU/L], morning cortisol level was normal [ 7.1 ug/mL] and a normal response to 1 mg dexamethasone suppression test. Transvaginal/Transabdominal ultrasound showed a left adnexa of 11.7×5.5×8.3 cm and simple cystic mass with no internal septations or nodularity and unremarkable right adnexa. Imaging by CAT scan showed a 9 cm left adnexal mass likely cystadenoma with unremarkable liver, spleen, pancreas and adrenals. Considering the laboratory, imaging findings and onset of symptoms the androgen production favors left adnexal cyst as the origin and not from the adrenals. Patient then underwent bilateral salphingoophorectomy without any complications and pathology reports revealed left serous cystadenoma. During her 2 week and 3 month post op follow up, patient reports no improvement of her hirsutism and virilization while repeat labs postoperatively showed normalization of total [15 ng/mL] and free testosterone [1.5 ng/mL]. Conclusion In conclusion, we report a rare case of androgen producing ovarian serous cystadenoma with virilizing features.