A correlation between the continuity of the cerebral blood flow pattern and the cerebral vascular resistance (namely, cerebral arteriosclerosis) was investigated by the Doppler ultrasonic technique. The following facts were observed. Examination of the brachial blood flow pattern in circulatory stress, i.e., hand-grasping, brachial-binding, cold- and warm-stimulating tests revealed that the more the peripheral vascular resistance was increased, the more was the discontinuity of brachial blood flow pattern increased. Investigation of the continuity of the cerebral blood flow pattern (internal carotid artery) in 18 young healthy persons and 46 elderly patients with cerebral vascular diseases revealed a continuous pattern in all of the young persons, while the discontinuous pattern was frequently observed in the elderly patients. These findings suggest that the cerebral vascular resistance is more increased in the elderly patients than in the young persons. The cerebral blood flow pattern was classified into the following three types according to the continuity of the cerebral blood flow pattern: continuous, intermediate and discontinuous type, and the relation to the Continuous Index (CI), which was devised as an objective parameter of the continuity, was examined. The following CI figures were obtained: 110-200% in the young persons; in the elderly patients: continuous type, 120-185%; intermediate type, 85-135%; discontinuous type, 50-85%. From the above findings it is postulated that the Doppler ultrasonic technique is useful for the quantitative detection of cerebral arteriosclerosis, i.e., anticipation of cerebral vascular accidents, and for the discrimination between arteriosclerotic dementia and Alzheimer's disease.