['Mitochondrial DNA (mtDNA) copy number correlates with tumor pathology in some cancers.', 'To investigate mtDNA copy number in head and neck cancer (HNC).', 'mtDNA copy number was determined and compared between HNC patients and malignancy-free controls.', 'The mtDNA copy number was significantly higher in HNC patients, increased with cancer progression and correlated negatively with patient survival.'] Is mitochondrial DNA copy number associated with diagnosis and prognosis of head and neck cancer?