Objective: To determine the prevalence of Criterion A traumatic events and current posttraumatic stress disorder (PTSD) and major depressive disorder (MDD) in prisoners in Kocaeli Closed Prison. Method: The study was conducted in Kocaeli Closed Prison in Turkey. The sample consisted of 30 female and 30 male prisoners who had been in prison for at least 1 month. The PTSD and MDD section of the Structured Clinical Interview for DSM-IV and the Traumatic Events Screening Instrument for Adults were used by experienced clinicians. Results: Most (n = 52, 86.7%) participants reported lifetime exposure to at least 1 Diagnostic and Statistical Manual of Mental Disorders (4th ed.) PTSD Criterion A event. Although the August 17, 1999, earthquake was the most prevalent traumatic event (n = 31, 51.7%), it was not related to the risk of current PTSD in prisoners. Current PTSD was rare among men (n = 2, 6.7%) and women (n = 3, 10%) but more prevalent than in community surveys of adults. Traumatic events that were relatively unique to the incarcerated population (e.g., committing murder) were identified. Moreover, 17% of women (n = 5) and men (n = 5) were diagnosed with MDD. Traumatic events that had the strongest conditional probabilities of association with a diagnosis of PTSD and MDD were identified. Conclusion: Exposure to traumatic stressors was highly prevalent among prisoners. Ongoing interpersonal traumatic events were particularly likely to be experienced as traumatic and related to PTSD and MDD, and violent criminal acts may be highly traumatic for the perpetrator.