The mitochondrial genome DNA copy number is critical for the functional maintenance of the mitochondria and energy acquisition for cell metabolism. Epithelial to mesenchymal transition (EMT) is an important process during embryonic development and has also been hypothesized to exhibit a significant role in cancer cell invasion and metastasis. In the present study, EMT was induced in the A549 non-small cell lung cancer (NSCLC) cell line, using transforming growth factor-β1 (TGF-β1) and changes in mitochondrial content, mitochondrial DNA (mtDNA) copy number and protein cytochrome c (Cyt c) were determined by reverse transcription-quantitative polymerase chain reaction and western blot analysis, respectively. mtDNA copy number and Cyt c protein levels were observed to increase following the induction of EMT in NSCLC cells. Results of the current study indicate that energy metabolism is adapted to facilitate EMT in NSCLC cells.