International relief and development personnel may be directly or indirectly exposed to traumatic events that put them at risk for developing symptoms of Post-traumatic Stress Disorder (PTSD). In order to identify areas of risk and related reactions, surveys were administered to 113 recently returned staff from 5 humanitarian aid agencies. Respondents reported high rates of direct and indirect exposure to life-threatening events. Approximately 30% of those surveyed reported significant symptoms of PTSD. Multiple regression analysis revealed that personal and vicarious exposure to life-threatening events and an interaction between social support and exposure to life threat accounted for a significant amount of variance in PTSD severity. These results suggest the need for personnel programs; prede-ployment training, risk assessment, and contingency planning may better prepare personnel for service.