Case report of bilateral occlusion of the internal carotid artery diagnosed by cerebral angiography: carotid angiography of both sides and vertebral injections were performed. The arterial occlusion as shown in right and left carotid angiography has the same shape in both instances and it lies just above the origin of the ophthalmic artery. By injecting the contrast fluid into the left vertebral artery the whole arterial field of the brain was filled. Introduction of contrast medium into the vertebro-basilar system when both carotid arteries are blocked has been reported as very harmfull and a dangerous procedure; nevertheless it was well tolerated in this case as have been controlateral injections of contrast in our cases of one sided occlusion of the carotid artery and its branches. Concerning the etiological problem in this case, since there is no evidence of acquired lesion, the condition is more likewise to be of congenital origin; this view point is supported by the patient's age (nine years) and by the similarity of the internal carotid arteries's shape in both sides.