The present study was intended to investigate personality characteristics and mental health of severe driving under influence (DUI) offenders in a Swedish cohort. More specifically the aim was to investigate the personality traits as assessed by The NEO personality inventory (NEO-PI-R) and aspects of mental health as assessed by the symptom checklist (SCL-90) as compared to the general population. The subjects were 162 severe DUI offenders (with the BAC >0.099%) with an age range of 18-88 years, 143 males and 19 females. It was found that the openness to experience and conscientiousness scales of NEO-PI-R differentiated Swedish DUI offenders from Swedish norm population. The differences between the DUI group and the general population on the on SCL-90 scales were all significant except on the Hostility scale. Two main subtypes of DUI offenders identified were roughly comparable to types I and II alcoholics, as in Cloninger's typology. Among all the scales used (personality traits, psychiatric comorbidity and alcohol use), the only factor that was predictive for future relapses to drunk driving was the factor of depression.