The single cell gel electrophoresis (comet) assay is one of the useful tools for the study of genetic damage in humans exposed to environmental mutagens and carcinogens. This study was undertaken to evaluate the status of DNA damage in peripheral lymphocytes depending on their sex, age, smoking habits, and other factors in normal healthy Korean population. The 99 volunteers included in the study and out of these, 36 volunteers were smoker and 63 volunteers were non-smoker aged between 20-59 years. All individual answered a questionnaire that assessed their general information including smoking habits and the extent of the environmental tobacco smoke (ETS) exposure, and blood samples were obtained. There was a statistically significant difference in the extent of DNA damage between smoker and non-smoker (p<0.001). A significant difference was also observed between male and female (p<0.001) and amongst the different group of age (p<0.005), however, correlation analysis showed that only smoking habit was a significant factor for DNA damage. No significant effect of smoking duration, number of cigarettes smoking a day, SPY (smoke pack years) in smokers and environmental tobacco smoke exposure in non-smokers on the status of DNA damage was observed.