The effect of two different doses of selenium [1 and 50 microg selenium/100 g body weight (wt)] on nicotine-induced oxidative damage in liver was investigated in experimental rats. Male albino rats were maintained for 60 days as follows: (1) control group (normal diet), (2) nicotine group (0.6 mg/kg body wt)/day, (3) high-dose selenium (50 microg/100 g body wt)/day, (4) high-dose selenium (50 microg/100 g body wt) + nicotine (0.6 mg/kg body wt)/day, (5) low-dose selenium (1 microg/100 g body wt)/day, and (6) low-dose selenium (1 microg/100 g body wt) + nicotine (0.6 mg/kg body wt)/day. Nicotine administration caused a decrease in the activity of antioxidant enzymes, an increase in the concentration of lipid peroxidation products and protein carbonyls and an increase in the activity of nitric oxide synthase compared to the control group. Coadministration of nicotine and selenium reduced the concentration of lipid peroxidation products and increased the activity of antioxidant enzymes compared to the nicotine group. Selenium also enhanced the metabolism of nicotine. The antioxidant effect was more significant in the group administered a low dose of selenium.