A postmenopausal patient presented with a pelvic mass and ascites. The CA-125 level was 329 U/ml, and transvaginal color Doppler sonography of the tumor vasculature suggested malignancy. At laparotomy, a luteinized thecoma and cytologically benign ascites were found. On rare occasions ovarian thecoma may be associated with ascites without hydrothorax. Preoperative evaluation of the patient with ascites and a pelvic mass may suggest malignancy, but histologic confirmation is necessary to exclude this rare association.