We report the cases of a mother and son with Leber's hereditary optic neuropathy (LHON), where a point mutation of mitochondria DNA from guanine to adenine on nucleotide position 11778 was verified. Both also had cerebellar ataxia and dysarthria and in both cases cerebellar atrophies were detected by computed tomography or magnetic resonance imaging. It was not possible to elucidate the relationship between LHON and the cerebellar atrophy, but it should be kept in mind that various neurological complications may occur in LHON.