The antigenotoxic effects of curcumin alone and with piperine on benzo(a)pyrene-diol (BaP) epoxide DNA adducts (BaPDE-DNA adducts), and carcinogen biotransformation enzymes was investigated in liver and lung of mice. Male Swiss albino mice received curcumin (100 mgkg(-1) body weight) and piperine (20 mgkg(-1) body weight) separately as well as in combination orally in corn oil for 7 days as pretreatments and thereafter 2 h, BaP (125 mgkg(-1) body weight) was administered orally in corn oil. A single dose of BaP to normal mice increased the activities of ethoxyresorufin o-deethylase (EROD), pentoxyresorufin o-depentylase (PROD) and levels of BaPDE-DNA adducts in both the tissues. Quinone reductase (QR) activity was also elevated in the BaP-treated group in both liver and lung when compared with normal control group. Pretreatment of curcumin and curcumin plus piperine before administration of BaP significantly decreased the activities of EROD, PROD, and the level of BaPDE-DNA adducts with consequent increase in QR activities. The study clearly indicates that curcumin, when given in combination with piperine, is more effective in modulating BaPDE-DNA adducts (liver and lung), and activity of EROD (liver).