This study compared the acute stress disorder and post-traumatic stress disorder (PTSD) symptom profiles in motor vehicle accident survivors who sustained a mild traumatic brain injury (MTBI) or no TBI. Consecutive adult patients who sustained a MTBI (n = 79) and no TBI (n = 92) were assessed for acute stress disorder within 1 month of their trauma and reassessed for PTSD (MTBI: n = 63; non-TBI; n = 72) 6-months post-trauma. Comparable rates of acute stress disorder and PTSD were reported in MTBI and non-TBI patients. Intrusive memories and fear and helplessness in response to the trauma were reported less frequently by MTBI than non-TBI patients at the acute phase. Six-months post-trauma fewer MTBI patients than non-TBI reported fear and helplessness in response to the trauma. These findings suggest that, whereas impaired consciousness at the time of a trauma may reduce the frequency of traumatic memories in the initial month post-trauma, MTBI does not result in a different profile of longer-term PTSD.