To explore alterations in γ-aminobutyric acid (GABA) levels in response to levetiracetam (LEV) treatment in patients with migraine. Patients with migraine (N=14) were treated with LEV for 12 weeks. The levels of GABA+ in the anterior cingulate cortex/medial prefrontal cortex (ACC/mPFC) and the posterior cingulate cortex (PCC) were examined by proton magnetic resonance spectroscopy before (baseline) and after treatment. LEV showed good efficacy in the reduction of headache frequency and intensity in patients with migraine. Among the 14 patients, good-quality spectral data of GABA+ in the PCC region were obtained in 11 patients. There was a significant decrease in GABA+ levels in the PCC region after LEV treatment. ACC/mPFC GABA+ was assessed by proton magnetic resonance spectroscopy in eight patients with migraine. LEV had no significant effect on GABA+ levels in the ACC/mPFC region. The decreased GABA+ levels after LEV treatment in patients with migraine suggest that GABA is a migraine biomarker.