The Leigh syndrome (LS), characterized by psychomotor retardation, seizures, nystagmus, ophthalmoparesis, optic atrophy, ataxia, dystonia, or respiratory failure, is one of the most severe mitochondrial diseases. In the majority of cases, the disease is fatal and patients die before age 5. Mutation m.10197 G>A was found to relate to the severe phenotype of the Leigh syndrome. Here, we describe the first Chinese Leigh syndrome pedigree with this mutation. The proband had the characteristic brain lesions of the Leigh syndrome and presented a decrease in exercise tolerance and mild face paralysis. Sequencing the NADH dehydrogenase, subunit 3 (ND3) gene in the pedigree, revealed that the proband, as well as her unaffected brother, have a high mutant load in the ND3 gene, compared to their mother. Following one‑year treatment with the coenzyme Q10, an obvious improvement in clinical features was observed by magnetic resonance imaging (MRI) in the proband. Our study and previous reports highlight the variability of phenotypic expression of the m.10197 G>A mutation, and suggest that pathogenesis of the syndrome may be affected by a number of factors. This is the first report on successful treatment of an LS patient carrying the mutation m.10197 G>A with the coenzyme Q10, indicating that Q10 may attenuate the mitochondrial dysfunctions caused by the m.10197 G>A mutation.