Posttraumatic stress disorder (PTSD) often afflicts victims of traumatic events such as combat. Growing evidence suggests that PTSD is related to poorer health status and to increased use of health care services. However, the extent of these effects and the means by which they occur remain unclear. The goal of this study is to enhance our understanding of both the extent and means by which PTSD affects the health and the health care use of patients in VA ambulatory care. To meet this goal, we built on an HSR&D service-directed project, the Veterans Health Study (VHS), a prospective longitudinal study of 2,425 male VA ambulatory care patients.