An unusual case of a huge primary ovarian fibrosarcoma, the largest tumor of its type reported to date, is presented. The gross, light microscopic, and ultrastructural features are described. The tumor was unique in three aspects: (a) its massive bulk; (b) the prompt relief of symptoms after debulking; and (c) most significantly, the lack of extensive abdominal metastasis in spite of its high grade, large size, and 6-month delay in resection.