OBJECTIVE To evaluate the clinical applicability of cellulose porous beads (CPBs) as an embolic material for permanent vascular occlusion. METHODS Embolization with CPBs was performed in 16 patients, six with meningioma of the sphenoid wing, two with meningioma of the falx, three with meningioma of the tentorium, two with dural arteriovenous fistula, one with paraganglioma, and two with spinal arteriovenous malformation. Surgical specimens were examined histologically. RESULTS No complications were encountered in any of the 16 patients. Angiograms obtained after embolization showed satisfactory vascular stasis in all cases. Histologic examination of surgical specimens disclosed that vessels having approximately the same caliber as the CPB particles were occluded without stretching of the vessel wall. Larger vessels were occluded by aggregates of many particles, which left no open spaces. Although a few inflammatory cells were seen in the thrombosed vessels, inflammation evoked by CPB was mild and did not extend to either the vessel wall or to surrounding tissues. CONCLUSIONS CPBs were easy to inject through microcatheters, traveled to distal sites, and produced homogeneous and peripheral embolization without inflammatory changes different from other embolic materials. CPBs are a good embolic material for permanent occlusion in the clinical setting.