Aim: Present study was aimed to examine relationship between the levels of MDA, end of products of lipid peroxidation, and paraoxonase (PON 1) which prevents development of atherosclerosis activity levels in smokers.

Materials and Methods: Sera from total of 49 male subjects aged between 45±5 years (22 chronic smokers, 27 controls) were used in the study.To determine serum paraoxonase activity, paraoxon was used as substrate.

Findings: PON activity and concentrations were found to be statistically lowered (p<0.001) whereas MDA levels were significantly higher in smokers compared to controls (p<0.05). There was a negative correlation between PON concentrations and MDA levels (r= -0.432, p<0.05)

Conclusion: Reduced serum PON 1 activity and concentration and elevated lipid peroxidation levels may be a cause of high incidence of cardiovascular originated diseases in heavy smokers.