Purpose: This study was to identify which factors are likely to influence the effectiveness of smoking cessation on adults who smoke in Metropolitan Incheon. Method: Data from 9,083 smokers, who visited a smoking cessation clinic of a public health center from Jan. to Oct. 2005, were provided by the Korean Health Research Society, Among 9,083 smokers, 1,495 people were selected for follow up care at 6 months in order to analyze the differences between two groups one is a successful group and the other is a failure group. Results: The successful group included 639 people and the failure group 856 people. In the demographic profiles such as sex, age and motive registration, there was a significant difference between the two groups. In the view of smoking pattern and factors such as the expiratory CO level, the age of starting to smoke, the duration of smoking, alcohol, and dependence on alcohol use and nicotine, there were significant differences between the two groups. The smoking cessation method, results of uni variate analysis, the total number of visits to the smoking cessation clinics, and the use of nicotine gum or a patch(stage 1, stage 2) were significantly different in the two groups. Conclusion: The results of multi variate analysis have shown that the factors associated with the success for smoking cessation is the total number of visits to the smoking cessation clinic, and the dependence on alcohol.