PURPOSE: Hemangiopericytoma(HP) exhibits its pathologic findings different from those of meningioma or oth-erangiomatous tumor; and its clinical behavior is unique and prognosis worse than other cases. We reviewed the CT,MR and angiographic findings of HPs and evaluated differential radiologic points of comparison be-tween typicalmeningiomas and meningeal HPs. MATERIALS AND METHODS: MR(n=16), CT(n=5) and angiographic imaging(n=10) wereperformed in 18 pa-tients(M:F=12:6, mean age:45 years) with histologically proven primary HPs. We evaluated theimaging find-ings of HPs with respect to site, shape, size, signal intensity, enhancement characteristics,vascular signal voids, calcification, bony and adjacent sinus involvement, and angiographic findings. RESULTS:HPs were meningeal in 14 cases and nonmeningeal in four. Meningeal HPs were located in the parasagittalregion(n=8), convexity(n=3), intradural extramedullary space(n=1), choroid plexus(n=1), and ol-factorygroove(n=1). Nonmeningeal HPs were located in the masticator space(n=2), paraspinal area(n=1) and supraclaviculararea(n=1). The mean maximal dimension of tumors was about 5.4cm and their shape was papillary(n=8) orlobulated(n=7). MR images showed high(n=13) or iso(n=3) signal intensities on T2WI, and heterogeneity onT2WI(n=9). Vascular signal voids in the mass were seen in all cases, while in two cases, CT scanning showednodular dense calcification. Bone destruction was present in six cases, but no hyperostosis was found. In fivecases, the superior sagittal sinus was involved. Angiographic images revealed highly vascu-lar masses supplied bythe internal carotid artery(n=5), external carotid artery(n=8), descending scapular artery(n=1) andradiculomedullary artery(n=1), with delayed tumor blush during the capillary and venous phase in which there wasno arteriovenous shunt. CONCLUSION: HP is one of the extra-axial tumors in which there is hypervascularity,aggressive bony destruc-tion arising in the meningeal and extrameningeal area, and heterogeneous high signalintensity, as seen on T2WI. Calcification is rare.