Primary solid neoplasms of the greater omentum. Primary solid tumors of the greater omentum are rare, with only 42 reported cases. Malignant hemangiopericytomas constitute only three of these cases. The 40-year-old patient described in this report had abdominal pain, a palpable abdominal mass, early satiety, and weight loss. At laparotomy a large omental hemangiopericytoma was excised, and no other evidence of disease was grossly evident. Eighteen months after initial laparotomy, the patient had widespread progression of the tumor and, despite chemotherapy, died 2 months later. A review of reported cases shows that abdominal discomfort (56%) and mass (35%) are the most common clinical characteristics of a primary omental tumor. Weight loss, ascites, and peritoneal implants usually indicate malignancy. Rare long-term follow-up prevents definitive conclusions regarding therapy and prognosis. At present, surgical excision alone appears to be the treatment of choice, with no demonstrable benefit from either chemotherapy or radiation. 