Posttraumatic stress disorder (PTSD) may be associated with structural abnormalities in the amygdala. To better characterize amygdala volume in PTSD, the authors conducted a meta-analysis comparing amygdala volumes in PTSD patients and comparison subjects. Using electronic databases, the authors found nine studies comparing amygdala volumes in adult subjects with PTSD with amygdala volumes in comparison subjects (participants unexposed to trauma and participants exposed to trauma but without PTSD). Results showed no significant differences in amygdala volumes between the groups. Within each group, the right amygdala was significantly larger than the left, indicating an asymmetrically lateralized amygdala volume that is preserved in trauma exposure and in PTSD.