300 patients suffering from neurodegenerative diseases distinct from Leber hereditary optic neuropathy (LHON) were screened for the presence of mitochondrial DNA mutations. We report on nine patients, eight female and one male, who all harboured mutations at positions 13,708 and 15,257 of the mitochondrial DNA. Both mutations have previously been claimed to be associated with LHON. Based on our results, these mutations occur in a number of different neurodegenerative diseases and therefore cannot be regarded as "LHON" mutations.