Drunk driving not only causes public and individual harm but also leads to economic costs with severe consequences for society. Research on the Driving Under Influence (DUI) phenomenon in many countries was initiated to improve public safety, prevention and rehabilitation of the DUI offenders. Research results and experiences from other countries on DUI may not be directly applied to Swedish conditions because of different legislations, norms and attitudes towards drunk driving. The main purpose thus has been to investigate and analyse Swedish DUI offenders with respect to their alcohol problems, detection, crime records, psychosocial characteristics, personality traits and mental health. The main sample comprised 2 100 suspected DUI offenders from 17 police stations from all over Sweden. Alcohol problems were screened using Alcohol Use Disorders Identification Test (AUDIT). Detection was analyzed on the basis of information received from police authorities. Crime records were collected from Sweden s official crime statistics. From this sample of 2 100 suspected DUI offenders, 290 responded to an invitation to take part in the study of psychosocial problems assessed with the Addiction Severity Index (ASI). Additionally, 162 severe DUI offenders were assessed with the Neuroticism-Extroversion-Openness Personality Inventory - Revised (NEO-PI-R) and Symptom Checklist with 90 items, (SCL 90) for psychiatric symptoms. At least half of the suspected DUI offenders had alcohol problems, including those assumed offenders with a Blood Alcohol Concentration (BAC) below the allowed Swedish legal limit. Manner and time of detection of DUI are significant for the type of offender being identified. Criminality among Swedish DUI offenders is substantially higher than among Swedes in general. Swedish DUI offenders seem to be underprivileged in social dimensions including education and financial standing as compared to Swedish standard. DUI offenders have, despite low scores in Consc