The authors investigated if the estimated suicide risk for axis I disorders & sociodemographic factors was modified by personality disorders. Psychiatric disorders were evaluated by psychological autopsy in 163 suicide victims & by personal interview in 396 population-based controls. Personality disorders modify suicide risk differently for affective disorders, substance use disorders, smoking, life events during the last 3 months, & sociodemographic factors such as being single. Estimated suicide risk for sociodemographic factors & life events is not substantially altered following adjustment for affective disorders or substance use disorders. Findings suggest treatment of personality disorders is essential for suicide prevention. (47 refs.) JA