There has been growing interest in the concept of resilience and the question as to whether psychotropic medications or psychosocial treatments might have resilience-enhancing effects. This pilot study investigates resilience in a sample of patients with post-traumatic stress disorder (PTSD) before and after treatment. Effects of treatment with tiagabine, fluoxetine, sertraline alone, and sertraline with cognitive behavioural therapy on resilience were assessed using the Connor-Davidson Resilience Scale (CD-RISC). Changes in resilience after treatment were measured and response to treatment was predicted from demographic, resilience and baseline disability measures. Changes in resilience following treatment were statistically significant. Items that showed the greatest change related to confidence, control, coping, knowing where to turn for help and adaptability. Items showing the least change related to religious and existential aspects of resiliency, effort, acting on a hunch, decision-making and goals. In linear and logistic regression models, gender, baseline CD-RISC score, baseline Sheehan Disability Scale score and an individual item from the CD-RISC scale, ‘Sense of Humor’, were significant predictors of response to treatment. Treatment of PTSD significantly improved resilience and reduced symptoms in this sample. Further controlled studies are indicated.