We examined the occurrence of violent traumatic events, DSM-III-R diagnosis of posttraumatic stress disorder (PTSD), and PTSD symptoms, and the relationship of these variables to drug abuse severity. One-hundred fifty opioid-dependent drug abusers who were participants in a randomized trial of two methadone treatment interventions were interviewed using the Diagnostic Interview Schedule, the Addiction Severity Index, and the Beck Depression Inventory. Twenty-nine percent met diagnostic criteria for PTSD. With the exception of rape, no gender differences in the prevalence of violent traumatic events were observed. The occurrence of PTSD-related symptoms was associated with greater drug abuse severity after controlling for gender, depression, and lifetime diagnosis of PTSD. The high rate of PTSD among these methadone patients, the nature of the traumatic events to which they are exposed, and subsequent violence-related psychiatric sequelae have important implications for identification and treatment of PTSD among those seeking drug abuse treatment.