The purpose of this study was to investigate the brain gamma-aminobutyric acid (GABA) concentration and its relationship with clinical variables in patients with panic disorder (PD). Single voxel proton magnetic resonance spectroscopy ((1)H-MRS) scan was performed on 22 medicated subjects with PD and 25 age and sex-matched healthy comparison subjects. GABA and other metabolite levels were measured in the anterior cingulate cortex (ACC) and basal ganglia. GABA levels were significantly lower in the ACC and basal ganglia of PD patients relative to comparison subjects. Lactate and choline concentrations in the ACC in PD patients were also higher than in the comparison subjects. Our data suggested in part that alterations of the GABA function and the energy metabolism in ACC and basal ganglia may play an important role in the pathophysiology of panic disorder.