The hypotheses were that mentally disordered inmates, compared to nondisordered inmates, would have a history of more convictions and more convictions for violent offenses; and that among the mentally diordered, those with concurrent antisocial personality disorder (APD) would have more total convictions and more convictions for violent offenses. A representative sample of male inmate of the penitentiaries in Quebec, Canada, were examined. Mental health was assessed with the Diagnostic Interview Schedule. Criminal history data on each subject were obtained from the files of the Correctional Service of Canada. Comparisons were made between the 107 inmates who had suffered at least one episode of a major mental disorder and the other 349 inmates. The first hypothesis was not supported, since the study found that the criminal careers of mentally disordered and nondisordered inmates did not differ significantly; however, the hypothesis that APD combined with major mental disorder increases the risk of crime was supported; the risk of violent crime, however, did not increase. The findings thus indicate the existence of two distinct groups of mentally disordered inmates. 1 figure, 2 notes, and 43 references