Cigarette smoking is a major risk factor of atherosclerosis and has been reported to contain an abundance of free radical species which could be expected to deplete antioxidants such as vitamin C . The present study was designed to investigate the relationship between smoking, plasma lipid and lipoprotein concentration, and plasma vitamin C level. Fifty-five healthy male smokers and 32 non-smokers were investigated in the study. Mean age, body weight , BMI and blood pressure made no differences in both smokers and non-smokers. Significantly, smokers has higher plasma total cholesterol and LDL-C , and lower HDL-C /LDL-C ratio compared with non-smokers. Plasma level of thiobartiturin acid reactive substances(TBARS), indicator of lipid peroxidation and increased susceptibility of LDL towards lipid perosidation, were elevated in smokers(p<0.001), while the plasma vitamin C level of smokers was significantly lower than that of non-smokers(p<0.05), indicating that elevated lipid peroxidation are associated with decreased plasma vitamin C content. In non-smokers a significantly positive correlation was observed between dietary vitamin C intake and plasma levels, but no such association observed in smokers. Lack of such a relationship and the decreased plasma vitamin C level in the smokers suggest that smoking may cause increased turnover of the plasma antioxidant. Consuquently, the sustained free radical load derived from smoking causes an imbalance in oxidant/antioxidant status and it could be expected that cigarette smoking renders plasma LDL more susceptible to oxidative modification . In the present study the possible explanations for that cigarette smokers have a higher risk of cardiovascular disease include the changes of blood lipid and lipoprotein concentration, and plasma vitamin C status which might have protective functions against free radicals -medaited lipid peroxidation.