Studies were made on the groups of psychiatric symptoms of Neuro-Behçet's syndrome in six cases considered to be brain stem encephalitis, including one case of autopsy. Psychiatric symptoms appeared from one to eight years after neurological symptoms first occurred. This group of psychiatric symptoms can be divided roughly into the early-stage, middle-stage, terminal-stage and episodic groups. The initias-stage symptom group concerns mainly a change in, and regression of, personality, consisting of being childish, shallow, indifferent, careless, rude, slow in action, euphoric, or depressive. The middle-stage symptom group is made up of indifference, forced smiling, forced crying, amnesia, recent memory impairment, and disorder of sleep rhythm. The terminal-stage symptom group comprises the "lock-in" syndrome, which if advanced, will become Apallisches Syndrome. The episodic symptom group is made up of pathologically abnormal experiences such as hallucinations and delusions and symptoms due to a decline in the level of consciousness such as confusion, delirium and twilight state. Dementia hitherto mentioned in Neuro-Behçet's syndrome should be classified as subcortical dementia.