Posttraumatic stress disorder (PTSD) is seriously debilitating and common, with 5-10% incidence in general population and over 30% in combat veterans. PTSD symptoms include emotional dysregulation, intrusive, distressing trauma memories, nightmares, and ‘flashbacks’. Our laboratory has reported exaggerated a.) first-person emotional b.) psychophysiological and c.) neuroendocrine responses to trauma recall in combat PTSD patients, and altered brain corticolimbic responses in PET neuroimaging. Therapies incorporating “mindfulness” techniques (e.g. “Acceptance and Commitment”) reduce PTSD symptoms. However, efficacy studies of MBSR/MBCT for PTSD have not been published. Combat veterans with chronic PTSD are recruited from Ann Arbor PTSD clinic. Psychiatric diagnostic interviews (CAPS and MINI), self-report severity measures (PDS, IES-R, PTCI, DASS-21), and psychophysiological testing are administered before and after an 8 week mindfulness-based group therapy or active control intervention (TAU psychoeducation group). Testing involves traumatic recall using trauma-related and neutral autobiographical scripts. Heart rate (ECG), skin conductance (SCR), facial tension (frontalis EMG), and saliva cortisol responses are measured, as well as cortisol response to awakening. To date we have recruited n=8 PTSD patients (mean age 62±12, trauma exposure 35±9 years) and run one Mindfulness group. One patient withdrew, others showed high levels of participation (practice >30min/day). PTSD symptoms were significantly decreased post-intervention (total CAPS 64±11 vs. 38±12, p<.05) with the largest decrease in “avoidant” symptoms. At pre-intervention testing, all subjects had first person emotional (negative PANAS) and physiological (HR, SCR) responses to trauma recall. Post-intervention responses were variable, with some subjects showing decreased PANAS, HR, and SCR. A mindfulness-based therapy group was clinically acceptable to an initial pilot group of elder, chronic combat PTSD patients. Preliminary results suggest decreased PTSD symptoms post-intervention, further data (including active control intervention) are needed. Analyses are ongoing; and expect data from two additional groups will be available for oral presentation to SRI.