The molecular aetiology of many patients with motor neuron disease (MND) remains unknown. Recent evidence of mitochondrial dysfunction, in particular the finding of histochemical abnormalities and pathogenic mitochondrial DNA (mtDNA) mutations, has prompted us to investigate further the role of mtDNA abnormalities in a cohort of thirteen patients with atypical MND presentations by whole mitochondrial genome sequencing. No pathogenic mutations were detected suggesting that inherited mtDNA mutations are not a common cause of atypical MND presentations.