Objectives: This study identified the factors associated with successful smoking cessation for 6 months at a smoking-cessation clinic of a public health center in an urban area. Methods: The subjects of this study were 670 visitors to the smoking cessation clinic of Dongjak-Gu public health center in Seoul, from September 6, 2005 to March 24, 2006. The 274 visitors of them responded to the questionnaire with registration, which contained the information related to the study except that of registered card for the clinic. A dependent variable was success or failure in smoking cessation during the 6 month-smoking cessation program, measured the status of smoking cessation in each week by self-report. Independent variable included demographic information, the characteristics in using the clinic, health status and smoking related behaviour, exposure to other smokers in daily life and motivation. Multiple logistic regression model was used to find the factors associated with success of smoking cessation. Results: The success rate in smoking cessation for 6 months was 33.6%. Five pretreatment characteristics were identified as univariate predictors of continuous abstinence. Finally, age, job, and practice oriented motivation were associated significantly with the success of smoking cessation for 6 months from a multiple logistic regression analysis. The lower socio-economic smokers such as people having lower literacy level, lower income people, unskilled workers, and recipients by Medical Assistant Program were more likely to fail in continuous abstinence for 6 months. Conclusions: In order to increase the success rate in smoking cessation clinics of public centers, counselors should activate self confidence and practice oriented motivation of participants for smoking cessation.