BACKGROUND The physiological mechanisms of deep brain stimulation (DBS) are not completely clear. Our understanding of them may be facilitated with the use of proton magnetic resonance spectroscopy ((1)H-MRS). METHODS Serial (1)H-MRS of both thalami was performed during the course of DBS of bilateral globus pallidus internus in a patient with primary generalized dystonia. RESULTS Two days after microelectrode implantation, a pulse frequency of 185 Hz was applied for stimulation. It resulted in relief of symptoms and a decrease of Burke-Fahn-Marsden dystonia rating scale (BFMDRS) scores, and was accompanied by a prominent increase of N-acetylaspartate (NAA)/choline-containing compounds (Cho) ratio, a mild increase of NAA/creatine (Cr) ratio, and a moderate decrease of Cho/Cr ratio. Two weeks later, for a search of the optimal stimulation mode, the pulse frequency was switched to 60 Hz, which resulted in clinical deterioration and significant increase of BFMDRS scores. At that time, all investigated (1)H-MRS-detected metabolic parameters had nearly returned to the pretreatment levels. CONCLUSIONS Use of serial (1)H-MRS investigations of various brain structures during DBS in cases of movement disorders permits detailed evaluation of the treatment response, has a potential for its possible prediction, and may facilitate understanding of the physiological mechanisms of stimulation.