In brain death cases who showed nonfilling phenomena in the internal carotid angiograms, the blood flow velocity patterns of the common carotid arteries were characterized by involvement of a single systolic peak and a marked reverse flow component which had never been observed in healthy subjects.The individuality of each blood flow velocity pattern in the common, internal and external carotid arteries was made clear by placing the transducer in contact with the respective artery in a certain case. The Doppler signal from the internal carotid artery involving a signal from a reverse flow was slightly detectable, even if the blood pressure was elevated by norepinephrine infusion and the external carotid artery was temporarily compressed. The blood flow velocity pattern of the external carotid artery was similar to the pattern of the common carotid artery. The peculiar flow pattern indicates that a brain death case has a to-and-fro movement in the internal carotid blood flow and an external carotid escape of common carotid arterial blood.