Primary pulmonary hemangiopericytoma is a rare, potentially malignant tumor and assumes more malignant course than that originated in the soft tissue. It can be asymtomatic until attaining a large size within the lung. We report a case of malignant hemangiopericytoma of the lung in a 29 year old man. It represented as a sharply demarcated, huge homogeneous opaque mass in the right upper lobe. The cytologic and histologic features were that of malignant hemangiopericytoma.