Leigh syndrome is a heterogeneous disorder, usually due to a defect in oxidati ve metabolism. Mutations in SURF1 gene have been identified in patients with cyt ochrome c oxidase deficiency. We report a homozygous splice site deletion [516- 2 516-1delAG] in a young girl presenting with cytochrome c oxidase-deficient L eigh syndrome. Identification of molecular defect is indispensable for genetic c ounselling and prenatal diagnosis. Mutations in SURF1 gene have been identified in patients with cyt ochrome c oxidase deficiency. We report a homozygous splice site deletion [516-2 516-1delAG] in a young girl presenting with cytochrome c oxidase-deficient Leigh syndrome. Identification of molecular defect is indispensable for genetic c ounselling and prenatal diagnosis.