Understanding the development of posttraumatic stress disorder (PTSD) implicates research regarding factors besides the preceding traumatic event. This study investigated the influence of predisposing personality traits on development of PTSD in a group of Danish Soldiers deployed to Afghanistan (N = 445). Using a prospective design data was collected using questionnaires including the NEO Five Factor Inventory and the Posttraumatic Stress Disorder Checklist. The results showed a PTSD-prevalence of 9.2% in the total sample 2.5 years after homecoming. Using Kruskal-Wallis, Mann-Whitney U, and Spearman¡'s rho significant relationships were identified between pre-existing personality traits of neuroticism and agreeableness with development of PTSD symptoms 2.5 years after homecoming, however, a number of additional cofounders were identified.