Much confusion exists between post-concussive syndrome (PCS) and post-traumatic stress disorder (PTSD). This study evaluates the symptoms of both disorders, with the goal of illustrating their unique characteristics. A clinical neuropsychologist interviewed 41 males and 29 females who had previously received the diagnosis of PCS or PTSD. Each subject was asked to provide a highly detailed chronological history of the events which preceded, followed, and occurred during the traumatic event. While none of the PTSD patients reported a loss of consciousness or amnesia, 85.7% and 96.4% respectively, of PCS patients reported these symptoms. Other symptoms, such as intrusive recollections of the event, reluctance to discuss the episode, hypervigilance and nervousness while discussing the event were unique to PTSD patients. These results suggest that PCS and PTSD differ with respect to specific symptoms. PCS and PTSD appear to be mutually exclusive disorders in that patients who are involved in traumatic events develop either PCS of PTSD, but not both for the same event. The clinician should not rely on such symptoms to diagnose PCS or PTSD since an accurate diagnosis of whether a patient sustained either disorder depends on a detailed chronological history obtained from the patient and a careful review of the patient's medical records. (RJM)