We conducted a pilot study to investigate the feasibility, acceptability, and efficacy of an eight week “mindfulness-based” cognitive behavioral group therapy for chronic combat posttraumatic stress disorder (PTSD). Veterans seeking treatment at a Veterans Administration outpatient PTSD clinic (n=11) were enrolled in the study; five completed all eight sessions, three completed at least six sessions, and three dropped out after two sessions. The eight patients completing 6-8 sessions showed considerable compliance with assigned home exercises and significant post-treatment improvement in PTSD symptom severity, in particular “avoidant” symptoms. These pilot data suggest mindfulness-based group therapy as an acceptable and potentially beneficial intervention for combat PTSD that may affect specific symptom clusters of avoidance and guilt. Further study is needed to identify factors influencing acceptability and effectiveness.