BACKGROUND: Desmoplastic small round cell tumor (DSRCT) is a rare, aggressive, malignant neoplasm that has recently been characterized. It has not been associated with a primary visceral organ. In women, cases are even more rare and often have some ovarian involvement. CASE: An 11-year-old girl presented with abdominal pain, nausea, and vomiting. A CT scan revealed a large heterogeneous pelvic mass with cystic components and an 8-cm midabdominal mass. During exploratory laparotomy, the patient was found to have a pelvic mass measuring 12. 9 cm replacing normal ovarian tissue. The midabdominal mass was also removed. Pathology, cytology, and immunohistochemistry confirmed a desmoplastic small round cell tumor. Even with aggressive surgical and medical intervention, the patient died 11 months after initial diagnosis. CONCLUSION: We present a rare small cell tumor that is associated with ovarian involvement. The prognosis in these patients is extremely poor and very few survivals have been reported. Copyright 2000 Academic Press.