A sonic analysis system was developed for the detection of cervical and intracranial vascular disease. The system analyzes recorded sound signals converted to digital data, and plots the frequency, time interval after the QRS wave of the electrocardiogram, and amplitude on the graph using contour lines. Sonic analysis of 22 patients with and 23 patients without cerebrovascular disease identified a characteristic pattern of disease called the "circular pattern." Five of 10 patients with internal carotid artery stenosis, four of seven with cerebral aneurysms, three with cerebral arteriovenous malformation, and two of two with dural arteriovenous malformation showed the circular pattern. Only one of 23 control patients showed the circular pattern. This system is a promising method for cost-effective mass screening for the early detection of cerebrovascular disease.