Between October 1972 and October 1973, the first nationwide survey of the multiple sclerosis group of diseases in Japan was performed by the Multiple Sclerosis Research Committee of Japan, supported by the Japan Ministry of Health and Welfare. Reports on 1,084 patients with the multiple sclerosis group were collected: 509 patients with multiple sclerosis, 82 with Devic's disease, 357 with “multiple sclerosis possible,” and 136 with “other or unclassified demyelinating diseases.” The natural history in the present nationwide series of multiple sclerosis patients showed considerable similarity to that of patients in Western countries, suggesting that multiple sclerosis in Japan is essentially the same as that in the Western countries. However, the previously reported special characteristics of Japanese multiple sclerosis patients, namely, a higher rate of visual impairment at onset, a higher rate of optic nerve involvement during the course of illness, and a higher rate of Devic's disease, were reconfirmed in the present series.