The purpose of this study is to report an experimental model for the cerebral infarction by occluding a segment of the middle cerebral artery with artificial emboli. In each dog the right common carotid artery was exposed and the internal carotid artery was catheterized selectively with a 16 gauge catheter of Intracath. The prepared embolus, a gutta percha cylinder measuring 4 mm long by 1.5mm in diameter was injected through the catheter of Intracath until backbleeding indicated the embolus had lodged intracranially, beyond the internal carotid-maxillary artery junction. The optimal material for experimental emboli should be radiopaque and easily identified in pathological specimens, and should produce cerebral lesions which resemble spontaneously occuring clinical infarction in pathophysiological mechanism. Since the gutta percha cylinder is radiopaque and its position was able to be checked in simple skull films, it was considered to an optimal embolic material. In the postoperative period the animals were extremely ill with impaired consciousness, vomiting and contralateral hemiplegia. Autopsy revealed massive hemorrhage infarction of the ipsilateral cerebral hemishpere in each of the animals and the average volume of infarction was 1.93 cu cm and also it was observed that there was no endothelial damage of the middle cerebral artey, even when the embolus was left in situ for 10 days.