The present study is concerned with a group of 50 psychotic patients with psychopathic personalities, encountered in New Guinea and the Philippines during World War II. The heredity, environmental background, personality development, and psychopathology were investigated. Fifty psychopaths not considered to be psychotic were used as a control group.Among the 50 patients the family setting was characteristically insecure. Enuresis, nail biting, temper tantrums, and sleepwalking were common. The scholastic performance and school adjustment were poor. The work record was characterized by frequent shifts in jobs, periods of unemployment, and difficulty in getting along with fellow workers and employers. Difficulties in developing and maintaining satisfactory interpersonal relationships were also common. Over two-thirds of the patients had a record of from one to 30 military or civilian arrests. Sexual life was marked by promiscuity and poor marital adjustment. In 6 there was a history of homosexuality. Of the 24 who had been married, 14 were divorced or separated.In 24 cases there was evidence of a previous neurotic or psychotic illness. Twenty-two were alcoholic. Five were addicted to drugs.During the psychosis the commonest psychopathological features were excessive motor activity, depression, auditory and visual hallucinations, paranoid delusions, disorganization of thinking, bizarre behavior, and defective judgment. In 22 cases suicidal preoccupations were found. Ten had made suicidal attempts. The dynamic factors and type of reaction were similar to those found in prison psychosis.