A 45-year-old postmenopausal woman, Gravida(6), Para(4), Abortus(0), Dilatation x Curhetage(2), came to the gynaecology department with pelvic pain. The tumor had arisen in the right ovary and measured 15 x 12 x 7 cm. Its cut surface varied from grey-white with a whorled appearance and showed areas of haemorrhage. Histologically the tumor was densely cellular, composed of spindle cells, diffusely involved the entire ovarian stroma with no normal ovarian structures remaining. Tumor cells had hyperchromatic nuclei with prominent nucleoli. There was moderate pleomorphism and the number of mitotic figures was an average of 6 per 10 high powerfields. In the immunohistochemical study, the tumor was negative for desmin, muscle-specific actin, estrogen, progesterone receptors and CD31, but was positive for vimentin. A low proliferation index with Ki-67 was determined. The patient has shown no evidence of recurrent disease for five years.