Intra-abdominal hemangiopericytomas are rare lesions, accounting of only 10% of all hemangiopericytomas. A total of five cases are reviewed: two malignant gastric lesions, two intraperitoneal malignancies, and one "benign" pancreatic lesion with a malignant hepatic recurrence. The images obtained by ultrasonographic and CT studies corresponded either to predominantly cystic or to solid lesions. Aside from the 50% of hemangiopericytomas that are malignant from the outset, the major problem with such lesions is the uncertain nature of their natural course.