The concept of medicalization suggests that a wider range of behaviors is being defined as legitimate for medical intervention, including behavior perceived as deviant or criminal behavior. In both years the arrest rates for the patient groups exceeded those of the general population. These higher rates were explained by the increasing number of patients with prior police records. Patients without prior arrests had lower arrest rates after release than the general population for all crime categories except property crimes. Comparison of these data with data gathered on patients released in 1946-47, showed that over a 30-year period the proportion of males with police records admitted to psychiatric facilities has steadily and consistently increased. While the reason that a case does not reach trial probably has as much to do with the strength of the prosecutor's case as it does with the mental state of the defendant, the decision to allow a person to be sent to a mental hospital instead of proceeding with trial is a process for which little data exist. Yet the study data strongly suggest that the availability of beds in State psychiatric facilities as opposed to the unavailability of beds in prisons has provided an opportunity for the medicalization of criminal behavior, which in turn has resulted in the greatly increased rates of arrest among former mental patients. This medicalization may have occurred without any ideological shifts. Data indicate that policymakers should exercise restraint in enacting legislation on the basis of misleading data showing that the overall rates of arrest of former mental patients greatly exceed those of the general population. Tables and 31 references are provided. (Author abstract modified)