In a sample of 205 hospitalized schizophrenics, 59 men were found who made verbal threats to kill or physical attacks some time during their illness. All homicidal aggression occurred during active phases of psychosis, typically in a setting of acute excitement and in recurrent illnesses. Paranoid diagnoses were overrepresented. Closely related females were the prime targets, suggesting a resentment of dependence on a woman. An impersonal, compulsive urge appears to be the motivating force leading to physical attacks.