To evaluate the impact of posttraumatic stress disorder (PTSD) on health-related functioning, we assessed 800 U.S. Army soldiers before and after 1-year military deployments to Iraq. As part of the Neurocognition Deployment Health Study procedures, each soldier completed at both time points self-report indexes of PTSD symptom severity, health behaviors (smoking, alcohol use), and somatic health-related functioning. Participants also completed a health-symptom checklist at the postdeployment assessment. Structural equation modeling revealed that postdeployment PTSD severity was associated with change in somatic health-related functioning, with postdeployment health symptoms as an intermediary variable. These relationships were independent of health risk behaviors, which had little association with somatic symptoms or PTSD. Our findings highlight the functional impact of PTSD, which extends beyond psychological symptoms to health-related daily functioning.