['To index the extent to which treatment response in posttraumatic stress disorder (PTSD) is predicted by rostral anterior cingulate cortex (rACC) volume.', 'We used structural magnetic resonance imaging in a 1.5 T scanner to examine subjects with PTSD (n = 13), traumatized control subjects (n = 13) and nontraumatized control subjects (n = 13). Subjects with PTSD then participated in 8 sessions of cognitive-behavioural therapy, after which we reassessed them for PTSD.', 'According to voxel-based morphometry, treatment responders had larger rACC volume than nonresponders. Further, symptom reduction was associated with larger rACC volume.'] Does rostral anterior cingulate volume predict treatment response to cognitive-behavioural therapy for posttraumatic stress disorder?