Fibromatous tumors of the ovary are considered to originate from specialized ovarian stromal cells and account for approximately 4% of all ovarian neoplasms. These are mostly benign tumors with less than 1% having increased mitotic activity. If 1 to 3 mitoses per ten high power fields (HPF) are present, the tumor is considered low grade, and is called a cellular fibroma. If greater than 3 mitoses per 10 HPF are present, it is considered as a fibrosarcoma. In both cases the tumor is usually larger than a benign fibroma and carries a worse prognosis. We have met two cases of large ovarian fibrosarcoma and report these cases with the brief review of literatures.