Herzog S, Fogle BM, Harpaz-Rotem I, et al. - This study was sought to evaluate if dissociative symptoms predict risk for development of posttraumatic stress disorder (PTSD)using data from a 3-year prospective cohort study of a nationally representative sample of US veterans. Even after adjusting for relevant sociodemographic and trauma-related factors, and severity of PTSD symptoms at baseline, derealization symptoms predicted a nearly 5-fold increase in relative risk of incident PTSD. This is the first study suggesting that trait dissociative symptoms could be a key population-based risk factor for the development of PTSD in trauma-exposed US military veterans. These data add to the literature on PTSD that mainly targets stable or immutable risk factors like sociodemographic and trauma characteristics or peritraumatic emotional reactions for prognostication. It also highlights the possible clinical usefulness of evaluating, monitoring, and treating derealization symptoms in trauma-exposed U.S. military veterans at risk for PTSD.