The principal aim of this project is to conduct a Randomized Controlled Trial (RCT) to examine whether adding a twelve-session Multi-Component Yoga Intervention (MCYI) to the treatment regimen of Australian Vietnam Veterans suffering chronic Posttraumatic Stress Disorder (PTSD) leads to a significantly greater clinical improvement than conventional psychiatric treatment alone. Include 12 sessions with each session 3 hours duration- 4 days per week for 3 weeks i.e. total of 36 hours. The Multi-Component Yoga Intervention (MCYI) consisting of specific poses, breathing techniques, information about yoga techniques and practices, group processes, psychoeducation, relaxation procedures and meditation techniques in Vietnam War Veterans with chronic Posttraumatic Stress Disorder (PTSD) resistant to treatment has been developed. This project aims to evaluate MCYI through RCT method.