This article investigates the prevalence of traumatization and mental distress in a sample of 1,055 male European long-term prisoners as part of a wider study of the living conditions of prisoners serving sentences of at least 5 years in Belgium, Croatia, Denmark, England, Finland, France, Germany, Lithuania, Poland, Spain and Sweden. Data were collected in a written survey using the Posttraumatic Diagnostic Scale (PDS), the Brief Symptom Inventory (BSI) as well as questions on attempted suicide and auto-aggressive behavior. Participants experienced a mean of three traumatic events, with 14 percent developing a Posttraumatic Stress Disorder (PTSD) subsequently. In each national sample, more than 50 percent of the participants were in need of treatment because of psychological symptoms and nearly one-third had attempted suicide. (Published Abstract)