Homicide (murder, manslaughter, and infanticide) is classified by the relationship of offender to victim, circumstances, method, motive, or analysis of the dynamic characteristics of the incident. The report examines the psychiatric dimension of spouse homicide; sexual homicide; and homicides of parents, by siblings, of children, of neighbors, of strangers, or in furtherance of other crimes. Methods of killing are detailed. Homicide is classified as 'normal' and 'abnormal,' depending on the legal outcome (murder, Section 2 manslaughter, or insanity). In most years, at least one-third of murders are classified as abnormal; the most common diagnostic category associated with abnormal murder is depression, frequently involving a suicide attempt after the murder. Psychiatric diagnoses, alcohol, drugs, amnesia, and automatism are discussed in terms of their relationship to homicide. The article concludes that very few cases justify an insanity defense. Because it allows flexibility in disposal, a defense of diminished responsibility is preferred by both lawyers and defendants. A diminished responsibility defense is possible in cases where depressive psychosis, schizophrenia, paranoid states, organic disease, epilepsy, or significant degrees of mental handicap were present at the time of killing. Because of the inadequacy of present law, and degrees of indirect pressure from the Court on the psychiatrist, neurosis, acute emotional disturbances, and singular actions occurring during emotional crises are rejected as valid grounds for a defense of diminished responsibility. Psychiatric disposition of those found guilty of homicide is discussed. Four tables report homicide incidence, legal dispositions, insanity pleas and diminished responsibility defenses. Over 50 references are appended.