Nicotine, a major component of cigarette smoke, plays an important role in the development of cardiovascular disease and lung cancer in smokers. Lipid peroxidation is a process associated with the pathogenesis of atherosclerosis and the level of lipid peroxides is increased in smokers. In rats fed a high-fat diet, the tissue concentration of lipid peroxides was found to be increased. On nicotine administration along with a high-fat diet an additive effect was observed in lipid peroxidation and free radical scavengers. The activities of scavenging enzymes superoxide dismutase, catalase and glutathione reductase were found to be decreased, while the glutathione concentration and activity of glutathione peroxidase were enhanced.