1. A neuropsychiatric study of 108 hospitalized patients with acute poliomyelitis was made during the Boston epidemic of 1955. Of these, 46 patients were in respirators, 48 had paralytic poliomyelitis not requiring a respirator, and 14 had non-paralytic poliomyelitis.2. A delirium was observed in 17 patients who were acutely ill with bulbar or bulbospinal poliomyelitis. This delirium was characterized clinically by a varying level of consciousness, pleasurable hallucinatory experiences and frequent illusions and delusions. There was waxing and waning of disorientation and confusion with a shortened attention span. Imaginary experiences were often described by patients as "wakeful" or "vivid dreams." The delirium occurred with the acute toxic phase of illness and lasted an average of two weeks followed by complete recovery in those patients who survived.3. Psychological responses to acute poliomyelitis were studied in an attempt to delineate specific mechanisms involved. Rationalization, denial, and regression were often observed and have been described. The occurence of anxiety and depression at various stages of the disease is noted and discussed.4. The role of a psychiatrist as part of a hospital polio team is emphasized(5).