Although recent research has begun to describe the neural and genetic processes underlying variability in responses to trauma, less is known about how these processes interact. We addressed this issue by using functional magnetic resonance imaging (fMRI) to examine the relationship between post-traumatic stress symptomatology (PTSS), a common genetic polymorphism of the serotonin transporter (5-HTT) gene, and neural activity in response to viewing images associated with the 9/11 terrorist attack among a rare sample of high-exposure 9/11 survivors (n=17).