The article studied 2,094 mentally ill offenders who were adjudicated as partially or fully not criminally responsible due to mental disorders during the years 1980 and 1994 in Japan. Men were predominant. More than 60 percent of the participants had previously received psychiatric treatment. Schizophrenia and other psychoses were the most common diagnoses among both males and females. Females were more likely to be charged with violent crimes, and half of them committed homicide. Females attacked family members more often, and they were diagnosed with depression more often than were males. In contrast, males were more often charged with nonviolent crimes and had a greater number of criminal records. Despite the fact that persons diagnosed solely with personality disorders were largely excluded from the study, male mentally ill offenders still shared more negative demographic factors with male criminals in general, such as being unmarried, having a lower educational level, a poorer employment history, chaotic lives, and substance abuse problems. References