The possibility that posttraumatic stress disorder (PTSD) can develop following traumatic brain injury (TBI) has been the subject of considerable debate. The traditional view has held that impaired consciousness that occurs with TBI precludes encoding of the traumatic experience, and this prevents subsequent reexperiencing symptoms. This paper critically reviews available, empirical studies on PTSD in TBI populations and suggests that these two conditions can co-exist. The various mechanisms that may mediate PTSD following TBI are discussed, and special attention is given to issues that recognize the distinctive features of PTSD following TBI. These processes include implicit processing, biologically mediated fear conditioning, and reconstruction of trauma memories. Finally implications for assessment, treatment, and forensic investigation of PTSD in TBI populations are, addressed. This review concludes that TBI populations provide a useful means by which the role of traumatic memories (and impaired memories) in posttraumatic adjustment can be studied.