A sporadic case of a 31 year-old woman with genetically confirmed diagnosis of LHON was presented. Both her optic nerves were affected, with a 5-year interval between the onset in one eye and the loss of vision in the second one. Besides optic atrophy clinical and laboratory signs of multiple sclerosis were found. A review of the literature suggests that the G3460A mutation present in this case rarely coexists with a MS-like clinical phenotype.