The most important problem that humanity is facing in this century is environmental pollution. Polycyclic aromatic hydrocarbons (PAHs) are abundant pollutants and many of them are carcinogenic. The most important PAH is Benzo(a)pyrene [B(a)P] which is formed by the incomplete combustion of organic substances, cigarette smoke, charcoal and grilling of food. Benzo(a)pyrene [B(a)P]  has been shown to cause mutagenic, carcinogenic and cytotoxic effects in various species and tissues. The present study was aimed to divulge the cytotoxic effect of B(a)P induced oxidative damage in liver of male Swiss albino mice. Animals were divided into 3 groups of which Group I served as control and were given corn oil, Group II animals were administered with B(a)P (100 mg/kg body weight) dissolved in corn oil orally thrice a week for three successive weeks for an induction period of 6 weeks, Group III animals were  administered with B(a)P (100 mg/kg body weight) dissolved in corn oil orally thrice a week for three successive weeks for an induction period of  12 weeks. At the end of the experimental period, the extracted liver tissue was investigated biochemically for cytotoxic markers, oxidative stress markers, lipid peroxidation and antioxidant enzymes .The evaluation of these enzymes and their activities reflect the severity of damage caused to the membrane or to the organ itself.  The data suggests that the difference in morphology and cellular changes in liver on exposure to B(a)P is time dependent. Key words: PAH, B(a)P, toxicity, swiss albino mice,  liver, oxidative stress