Primary ovarian fibrosarcomas are very uncommon neoplasms. Since the diagnostic criteria were established in 1981, less than one hundred cases have been reported. This diagnosis can be difficult to establish and other similar appearing mesenchymal processes must be ruled out. In every case this diagnosis is under consideration. Multiple sections of the specimen and immunohistochemical stains will be necessary to support this diagnosis. The difficulty of recognition in frozen section in the majority of the situations implies that the diagnosis should be deferred to the definitive study of the permanent sections with immunohistochemical studies. There exists a histological resemblance between a primary ovarian fibrosarcoma and actively mitotic fibroma. In some cases, it can be impossible to separate exactly these two entities. We report a well-differentiated ovarian fibrosarcoma, with less than 1-2 mitosis HPF and low-grade cytological atypia, similar to active mitotic fibromas, developing liver metastasis one year later. Despite having distant metastasis, some cases with long survival rates have been reported in patients who received chemotherapy after surgery; so that the adjuvant chemotherapy should be considered, especially in young females.