Leigh syndrome (subacute necrotizing encephalomyopathy) is a progressive neurodegenerative disorder of infancy and childhood, with characteristic pathological hallmarks including symmetric necrotizing lesions in the subcortical structures , brainstem and spinal cord. It may result from several defects of mitochondrial enzyme complexes, including pyruvate dehydrogenase complex, and respiratory chain complexes I, II, III, IV, V. Leigh syndrome occurs with an estimated frequency of 1:77000-1:34000 live births. Symptoms usually start after a few months of normal development. There are the neurologic signs and regression to an early stage of development. Affected patients usually die to 6 months after first symptoms due to central ventilation failure. Biochemical abnormalities including elevated blood and CSF lactate and neuroimaging plays an important role in diagnosis as well as follow up of patients with Leigh’s Syndrom. Biopsy of muscle and genetic analysis for mutation detection has significant diagnostic and prognostic implication. It lack of effective treatment disorder. Author presents cases report of two children with Leigh’s syndrome recognized.