In Operation Iraqi Freedom and Operation Enduring Freedom, blast-related injuries associated with combat are frequent and can result in traumatic brain injury (TBI) symptoms that may be difficult to distinguish from psychological problems. Using data from the Post-Deployment Health Assessment and Reassessment, we identified 12,046 male U.S. Navy sailors and Marines with reported combat exposure from 2008 to 2009. Symptoms potentially associated with blast-related TBI and posttraumatic stress disorder (PTSD) that were reported immediately after deployment were compared with symptoms present several months later. Our study supports others that have found that subjects with blast-related injuries may experience the development or worsening of symptoms during the months following deployment. Additionally, our study found that those who screened positive for PTSD and TBI formed a unique group, with the presence of TBI exacerbating development of PTSD symptoms at reassessment. Providers should recognize the late development of symptoms, consider the possibility of comorbidity, and be prepared to treat multiple symptoms rather than a specific diagnostic category.