There is a lack of psychological autopsy studies assessing the influence of axis II disorders on other risk factors for suicide. Therefore, we investigated if the estimated suicide risk for axis I disorders and socio-demographic factors was modified by personality disorders. Psychiatric disorders were evaluated by a semi-structured interview including the Structured Clinical Interview for DSM-IV Axis I (SCID-I) and Personality Disorders (SCID-II) by psychological autopsy method in 163 completed suicides and by personal interview in 396 population-based control persons. Personality disorders modify suicide risk, differently for affective disorders, substance use disorders, smoking, life events during the last three months, and socio-demographic factors such as being single. Estimated suicide risk for socio-demographic factors and life events is not substantially altered following adjustment for affective disorders or substance use disorders. These findings suggest that treatment of personality disorders is essential for suicide prevention.