Recent data suggest that the cannabinoid-system is involved in stress regulation and posttraumatic stress disorder (PTSD). Low endocannabinoid signaling has been found in PTSD patients and might even present a precondition to develop PTSD after trauma. In consequence, increased endocannabinoid signaling during acquisition and consolidation of traumatic events might be a promising approach to prevent the development of PTSD. The aim of the current project is to investigate the impact of an activation of the cannabinoid system with an exogenous cannabinoid (dronabinol, i.e., delta-9-tetrahydrocannabinol) on tfear conditioning in patients with PTSD and healthy controls.