Leigh disease is a familial and degenerative disorder characterized by focal, bilateral, and usually symmetric lesions of the both gray and white matter in the brain and the spinal cord. The clinical course is variable, but in most cases, the prognosis is poor with subacute progression leading to death within months or years of life. The pathogenesis was known as mitochondrial enzyme defects of the respiratory chain system. We experienced 2 cases of Leigh diseases in a brother and sister. The brother had general weakness at 43 months of life and the sister had ataxic gait and tachypnea at 34 months of life. Their MRI revealed low signal intensity in the midbrain and pons at T1 weighted imaging. They died at 43 months and 41 months of life, respectively. We report these cases with a brief review of the related literature.