Correspondence of three core Trauma Symptom Inventory (TSI) posttraumatic stress disorder (PTSD) scales (Intrusive Experiences, Defensive Avoidance, and Anxious Arousal) and the Structured Clinical Interview for DSM-IV Axis I Disorders (SCID-IV) PTSD module were examined among 72 veterans with traumatic brain injury (TBI), PTSD, or both conditions. Subjects were classified into PTSD only, TBI only, or co-occurring PTSD and TBI groups based on TBI assessment and SCID-IV PTSD diagnosis. Linear regression was used to model TSI T-Scores as a function of group. Scores on all three scales significantly differed between the TBI and PTSD groups (PTSD only and co-occurring PTSD and TBI) in the expected direction. Study findings indicate that despite the potential overlap of symptoms between PTSD and TBI, the TSI appears to be a useful measure of trauma-related symptoms in veterans who may also have a TBI, particularly mild TBI. Limitations and areas for future research are discussed.