There is growing interest in using the quickly developing field of genomics to contribute to military readiness and effectiveness. Specifically, influential military advisory panels have recommended that the U.S. military apply genomics to help treat, prevent, or minimize the risk for post-traumatic stress disorder (PTSD) among service members. This article highlights some important scientific, legal, and ethical challenges regarding the development and deployment of a preventive genomic sequencing (PGS) program to predict the risk of PTSD among military service members.