Sixteen of 199 cases of disseminated sclerosis which have been the subject of detailed study were admitted to psychiatric hospitals sometime during the course of their illness. The early transient attacks of numbness or palsy are often considered to be hysterical manifestations. Sclerotic plaques often occur in the white matter of the forebrain and may produce mental symptoms. It is important also to take into consideration the fundamental behavior pattern of the individual and the personal reactions to the illness. Emotional instability was the basis for the difficulties which caused many of the individuals to consult a psychiatrist. Often overt sexual activity, sometimes associated with impotency, caused difficulties of adjustment. All patterns of maladjustment have been seen.