In a total of 303 cases the diagnosis of epidemic encephalitis was made at the Boston Psychopathic Hospital up to the end of 1934. Only 7 patients had the first symptoms prior to 1917; 25 had the acute attack after the end of 1926. The remaining 271 patients had the first symptoms in the epidemic years from 1917 to 1926 and were arbitrarily selected for this report. As a result of this investigation, 5 of the 271 patients were found to have been suffering from conditions other than epidemic encephalitis, namely cerebral syphilis, Sydenham's chorea, alcoholism and tumor of the brain, and were excluded. Of the total of 266 patients, information was obtained concerning the present condition of 240. Seventy-eight of these were admitted to the hospital within the first three months after the onset of symptoms. The remainder, or 162 patients, were afflicted with sequelae or were in a