In a large number of patients with Leigh syndrome (LS) and cytochrome c oxidase (COX) deficiency, mutations of the SURF-1 gene were recently identified. The aim of the present study was to review the MR findings in patients with LS to verify if the genetically homogeneous patients with LS and SURF-1 mutations (LS SURF-1 patients) had a homogeneous MR pattern that could be used to differentiate them from other patients with LS (LS non-SURF-1 patients).T1-, proton density-, and T2-weighted MR images of eight LS SURF-1 patients and 14 LS non-SURF-1 patients were reviewed. Enzymatic activity was determined according to standard methods. Genetic analysis was mostly performed by using stored DNA samples.All LS SURF-1 patients had lesions in the brain stem and subthalamic nuclei. Six had lesions in the cerebellum. Only two had basal ganglial abnormalities. Ten LS non-SURF-1 patients had lesions in the brain stem, but in six they were mild. Ten patients had basal ganglial abnormalities (nine of 10 in the putamina). LS-SURF-1 patients had a more severe clinical course.The MR pattern in LS SURF-1 patients is characteristic. Brain stem and subthalamic nuclei lesions may suggest the specific diagnosis. These patients die soon, probably because of lower brain stem involvement. Basal ganglial abnormalities are common only in LS non-SURF-1 patients. The absence of putaminal lesions, therefore, does not exclude the diagnosis of LS.