BACKGROUND: Although the Fagerstrom Tolerance Questionnaire (FTQ) and the Fagerstrom Test for Nicotine Dependence (FTND), which are the tools to measure Nicotine Dependence, have a high internal reliability and a high test-retest reliability, they have not been tested domestically. A Korean-Version Questionnaire for Nicotine Dependence was assessed to find out the internal reliability, test-retest reliability and validity. METHODS: The research subjects were adult smokers of ages between 19 and 77 among hospital visitors, hospital staffs, inpatients and outpatients. The smokers had their carbon monoxide measured after responding to the questionnaire. The questionnaire consisted of Nicotine Dependence (FTQ & FTND), the history of smoking, the variables related to Nicotine Dependence, and factors that influence carbon monoxide(CO) measurement. Micro II smokerlyzer (Bedfont Instruments Ltd, England) was used to analyze CO concentration in expired air. The method used for measuring CO concentration was to deeply inhale and hold one's breath for 15 seconds and measure CO concentration while exhaling. RESULTS: The total number of subjects was 205 (199 males, 6 females) consisting of 124 hospital visitors, 67 hospital staff, 8 inpatients, and 6 inpatients. The average FTQ was 4.68 and the average FTND was 3.95. Cronbach's alpha, which indicates the internal reliability, was 0.6679 for FTQ and 0.6913 for FTND. The correlation coefficient which indicates test-retest reliability was 0.783 for FTQ and 0.880 for FTND. The correlation coefficient which indicates the relationship between the level of Nicotine Dependence and expired air CO concentration was 0.484 for FTQ and 0.563 for FTND. The correlation coefficient of the smoking period was 0.247 for FTQ and 0.252 for FTND. CONCLUSION: This Korean-Version Questionnaires for Nicotine Dependence (FTQ & FTND) were both satisfactory from the aspects of reliability and validity. It was concluded that the Korean-Version of FTND was a reliable method to reflect the level of nicotine dependence of smokers from the fact that the reliability and validity of FTND was higher than that of FTQ.