In this paper we explore the evidence for post-traumatic stress disorder (PTSD) after traumatic brain injury (TBI). We examine its possible mediating mechanisms after brain injury, the evidence for its occurrence, risk, and protective factors, and the implications for intervention and service demands. In the first section we review the current literature relevant to cause, maintenance, and treatment of PTSD in general, before addressing issues associated with the assessment and management of PTSD after TBI. It is argued that PTSD may occur after a brain injury, and can be, relatively, a common disorder. However, explanatory mechanisms for its occurrence may be speculative. In this context, we argue, assessment and treatment need to be carefully considered, and comprehensive.