The modulatory effect of Withania somnifera along with paclitaxel on tricarboxylic acid (TCA) cycle key enzymes and electron transport chain complexes were investigated against lung cancer induced by benzo(a)pyrene in Swiss albino mice. Decreased activities of TCA cycle key enzymes such as isocitrate dehydrogenase (ICDH), succinate dehydrogenase (SDH), malate dehydrogenase (MDH) and alpha-ketoglutarate dehydrogenase (alpha-KGDH) in lung cancer bearing animals were observed. Upon W. somnifera along with paclitaxel administration the above biochemical changes were inclined towards normal control animal values. Activities of mitochondrial enzymes and electron transport complexes were analyzed in the experimental groups to determine the efficiency of energy production. This study further confirms the chemotherapeutic effect of W. somnifera along with paclitaxel which is found to be more effective in the treatment of lung cancer. Thus these results are consistent with our hypothesis that the combination chemotherapy of W. somnifera along with paclitaxel as a promising chemotherapeutic agent.