Takayasu arteritis is a disease on which many investigations have been conducted to determine its causes, clinical features and treatment, since 1908 when it was reported by Dr. Takayasu. The first nationwide epidemiological survey on Takayasu arteritis was conducted over 3 years from 1973 through 1975 by a research group on "aortitis syndrome", a disease specified by the Ministry of Health and Welfare. Another nationwide survey on this disease over a period of 3 years was carried out from 1982 through 1984 by a research group focusing on "systemic vascular lesion", another disease specified by the Ministry of Health and Welfare. The present study reports on the combined results of these two nationwide epidemiological surveys.