The authors describe a rare case of primary ovarian fibrosarcoma and the latest trends in diagnosis and therapy. The rarity of this dis-ease and the scarce number of reported cases pose serious problems in differentiating it from other fibrous forms. A 58-year-old woman presented intermittent pelvic pain and a demarcated, mobile, and solid lump in the right adnexa. Diagnostic imaging revealed a solid- cystic inhomogeneous mass occupying the right adnexa and the CA125 level was elevated. The patient underwent total hysterectomy with bilateral salpingo-oophorectomy and infracolic omentectomy. Histological findings with immunomarkers led to the final diagnosis of low-grade malignant mesenchymal neoplasm derived from the ovarian stroma compatible with fibrosarcoma. Twenty-four months follow-up showed no recurrence of disease. Ovarian fibrosarcoma is very uncommon neoplasm with a poor prognosis. Despite the efforts of several authors in reporting morphological, histological, and immunohistochemical features of this neoplasm, nowadays, the diagnosis, treatment, and prognosis are unresolved issues. The present case highlights the important role of immunohistochemistry to define histological type and differential diagnosis. As demonstrated by the authors' experience, they believe that surgery is curative in the early stages with low immunohistochemical positivity for ki67 and that chemotherapy should be reserved in advanced stages with regimens in use for the treatment of sarcomas.