The effectiveness of a new treatment for post traumatic stress disorder (PTSD) is addressed. Treatment was based on a metacognitive theory of mechanisms by which natural traumatic processing is enabled or hindered by coping strategies. It suggests that elimination of worry/rumination, of maladaptive attention strategies, and enhancing metacognitive flexibility, will permit natural processing and a return to normal cognition. An A-B direct replication series (n = 6) with follow-up assessments at 3, 6, and 18-41 months was implemented. Treatment commenced 3-10 months post-trauma. All patients showed large and statistically significant improvements in general emotion and specific PTSD measures. Gains were maintained at follow-up. Two further consecutively referred patients were treated at 8 and 12 months post-trauma to add to sample size (n = 8). Overall Post treatment effect sizes were large, ranging from 3.0 to 5.0. Further evaluations are clearly warranted.