The constellation of physical, cognitive, and emotional symptoms, collectively known as postconcussion syndrome (PCS), is not uniquely associated with concussion, making the etiology of chronic postconcussion symptoms controversial. The current study compared percentages of individuals meeting symptom-based criteria for PCS in a population-based sample of veterans composed of subgroups with various psychiatric diagnoses, a history of mild traumatic brain injury (MTBI), and healthy controls. Participants were identified from 4462 randomly sampled male U.S. Army veterans who served during the Vietnam era. Only 32% of veterans with a history of MTBI met DSM-IV symptom criteria for PCS as compared to 40% of those diagnosed with post-traumatic stress disorder (PTSD), 50% with generalized anxiety disorder (GAD), 57% with major depressive disorder (MDD), and 91% with somatization disorder. Results were consistent with existing literature showing that the PCS symptoms are not unique to concussion, and also provide important base-rate information for neuropsychologists practicing in both clinical and personal injury forensic settings.