Magnetic resonance spectroscopy (MRS) is a safe and non-invasive technique for the in vivo study of brain chemistry and metabolism. As such, it is highly applicable to the study of living brain tissue in psychiatric diseases. Several neuropathological and neuroimaging studies have suggested that abnormalities of the basal ganglia nuclei might be implicated in patients with obsessive-compulsive disorder (OCD). In the present study, we performed proton [ 1 H]MRS of the lenticular nuclei in 12 patients with OCD and 12 healthy normal comparison subjects. The peaks of N-acetyl-aspartate (NAA), creatine (Cr), and choline-containing compounds (Cho) were measured. No differences between OCD patients and normal subjects were found in the NAA/Cr, Cho/Cr and NAA/Cho ratios. Our results suggest the normal viability of neuronal cells, as indicated by the quantification of NAA, Cr and Cho in the lenticular nuclei of patients with OCD.