Primary ovarian rhabdomyosarcomas were found in 13 patients aged 7 to 79 (mean 37) years who had reported abdominal pain and swelling. Six tumors involved the right ovary, 3 involved the left, 1 involved both, and the laterality was unknown in 3 cases. Four tumors were stage I, 2 were stage II, 4 were stage III, and 2 were stage IV; the stage of 1 tumor is not known. The tumors ranged from 10 to 19.5 (average 16) cm in diameter and had solid sectioned surfaces that varied from yellow to white to pink and from gelatinous to hemorrhagic. Microscopically, 11 tumors were embryonal and 2 were alveolar rhabdomyosarcomas. Follow-up information, available for 11 patients, revealed that 7 died of disease 10 days to 26 months postoperatively; 2 of these patients had stage II disease, 3 had stage III, and 2 had stage IV. Four patients were alive 2 to 9 months postoperatively; 3 had stage I and 1 had stage III disease. These 13 tumors and an additional 10 from the English-language literature are reviewed and the differential diagnosis of ovarian rhabdomyosarcoma is discussed.