Background In recent years, true primary ovarian lymphoma has been considered to carry a favorable prognosis, although most studies of supposedly primary ovarian lymphoma have reported a poor outcome. Case A 47-year-old woman presented with signs and symptoms suggestive of an advanced ovarian cancer. Ultrasonography and magnetic resonance imaging revealed bilateral abdominal tumors, each measuring 10 cm in diameter, thickened omentum, and a large amount of ascitic fluid, but no enlarged lymph nodes. The diagnosis of malignant lymphoma was established from the biopsy specimen after exploratory laparotomy. Six years following chemotherapy, the patient is alive and disease free without additional surgery. Conclusion The prognosis of ovarian lymphoma was evaluated according to clinical stage, modality of onset, histologic type, and phenotype. It remains controversial whether this case can be considered truly primary ovarian lymphoma and not merely a localized initial manifestation of a generalized disease. But if this case of advanced ovarian lymphoma were not primary, it could still be managed successfully with chemotherapy appropriate for the specific histology.