Hemangiopericytomas are soft tissue sarcomas of vascular origin, comprised of pericytes. They have been reported in the extremities, head and neck, back, retroperitoneum, and abdomen. The criteria for the diagnosis and treatment are reviewed. Wide local ablation of the tumor is necessary to prevent local recurrence. Fifty per cent are malignant, although regional node spread is infrequent. Ultrastructural studies are necessary to differentiate hemangiopericytomas from other sarcomas. Long-term follow-up of all cases is essential for optimal clinical management.