The mentally retarded, mentally ill defendant calls attention to problems in the relationship between the legal and the mental health systems. This study looks at what happens to a group of retarded offenders found incompetent to stand trial. The study examines differences in court processing and final disposition between mentally retarded and nonretarded defendants found incompetent to stand trial. Virtually all subjects were diagnosed as being psychotic. The mentally ill, retarded defendants spend significantly more time in the hospital, more time in the hospital waiting to be returned to jail, and more total time incarcerated in the criminal justice/mental health system. At a final disposition hearing mentally ill, retarded defendants were significantly more likely to be rehospitalized and less likely to be released to the community. No mentally ill, retarded defendant in this study went to prison. The longer periods of incarceration may stem from an underlying lack of understanding about the ability of retarded defendants to achieve competency. Differences in court disposition may result from a court/mental health professional tendency to select dispositions which are thought to be more 'humane'.