The current study was designed to evaluate the effects of oral supplementation of the piperine on lung tumour initiation by orally applied benzo(a)pyrene (B(a)p). To evaluate the effects of orally supplemented piperine on lung tumour initiation by B(a)p, its effects on ATPase enzymes were first evaluated. Lung cancer bearing mice showed an increase in erythrocyte membrane and tissues ATPase enzymes (Na⁺/K⁺-ATPases, Mg²⁺-ATPases and Ca²⁺-ATPases). Na⁺ K-ATPase and Mg-ATPase enzyme activities were decreased and calcium ATPase increased (P < 0.05) in erythrocyte membrane and tissues of lung cancer bearing animals compared with control groups. The elevation of these enzyme activities in membrane and tissues were indicative of the persistent deteriorating effect of B(a)p in cancer bearing animals. These enzyme activities were reversed to near normal control values in animals treated with piperine (50 mg/kg body weight). It is apparent that the beneficial effect of piperine is primarily exerted on the during initiation phase and post-initiation stage of B(a)p induced lung carcinogenesis. Overall, these data indicative that piperine has chemopreventive effects when administered orally on lung cancer bearing animals.