Granulosa cell tumors (GCTs), adult type, are the most common type of ovarian sex cord tumors. Menstrual irregularity, even secondary amenorrhea is frequently observed in premenopausal women bearing GCTs with hormonal activity. We present here in an extremely rare case of adult GCT in a patient presenting with secondary amenorrhea and serum testosterone (Test) and luteinizing hormone (LH) elevations, and decreased estradiol (E 2). A 32-year-old woman visited our hospital complaining of secondary amenorrhea two years after second delivery. Signs of virilisatoin, such as increased pubic hair and clitoromegaly were present. A pelvic ultrasound scan revealed a right adnexal solid mass measuring 2.9x3.9 cm. Under the working diagnosis of sexcord tumor, the woman underwent a laparoscopic surgery of a right salpingo-oophorectomy and the tumor was collected from the Douglas' pouch. The tumor was diagnosed as an adult-type GCT stage IA. Spontaneous menstruation occurred and serum levels of Test, LH, FSH and E 2 showed normal ranges one month after surgery. The patient is now healthy without evidence of a recurrence 30 months after the surgery. Although s-Test and LH elevations in patients with GCT is rare and its mechanism is not clearly understood, monitoring of s-Test and LH may provide an additional tumor marker after conservative surgery in such patients.