A very rare large intraventricular hemangiopericytoma occurred in a 41-year-old male with a 2-month history of headache and paresthesia of the right shoulder and arm. The tumor was partially removed, followed by 50 Gy local Linac irradiation given over 6 weeks. Four months later the residual tumor demonstrated a marked decrease in size and vascularity. The residual tumor was totally removed with less operative bleeding than at the initial operation. This is the first reported case of hemangiopericytoma located in the trigone of the lateral ventricle.