The factor structure of posttraumatic stress disorder (PTSD) symptoms, and correlations between PTSD dimensions and substance dependence, were examined in 295 substance-abusing women. Participants completed self-report measures of trauma exposure, PTSD symptoms, and alcohol dependence and underwent interviews regarding dependence on prescription anxiolytics and analgesics. Overall, PTSD symptoms were moderate in intensity, and 46% of the sample met criteria for PTSD diagnoses. A principal-components analysis on PTSD item scores revealed a correlated 4-factor solution (i.e., Intrusions, Arousal, Numbing, and Avoidance factors). Alcohol dependence correlated with PTSD Arousal scores, anxiolytic dependence with Arousal and Numbing scores, and analgesic dependence with Arousal, Intrusions, and Numbing scores. Implications for understanding functional relations between PTSD and substance use disorders are discussed, as are suggestions for intervention with comorbid patients.Posttraumatic stress disorder (PTSD) is an DSM-IV; American Psychiatric Association anxiety disorder that can emerge after exposure [APA], 1994). In both the revised third edition to a traumatic stressor (i.e., when a person is (DSM-1II-R; APA, 1987 and DSM-IV definiconfronted with, experiences, or witnesses an tionsofPTSD, 17 symptoms are organized into event involving actual or threatened death or three clusters: Criterion B-Intrusions (e.g., serious injury, or a threat to the physical nightmares); Criterion C-Avoidance/Numbing integrity of the self or others, and when the (e.g., avoidance of trauma reminders; feelings of person's response involves intense helplessness, detachment); and Criterion D-Arousal (e.g., fear, or horror; Criterion A, Diagnostic and Stat-exaggerated startle). istical Manual of Mental Disorders (4th ed.;There is, however, considerable controversy