Background: There is very limited data present on smoking cessation rates in outpatient departments of pulmonology. In this study, we aimed to investigate the effectiveness of a brief smoking cessation intervention program in an outpatient department of pulmonology and identify predictors of smoking cessation failure. Methods: After a brief recommendation of smoking cessation from pulmonologists, smokers willing to quit smoking were given individual counseling and supplement drugs. Fifty smokers were included in this study and baseline characteristics, smoking history and success rate were reviewed at 3 months. Results: The mean age of the patients was $58.3{pm}14.6$ years and the total group of patients included 3 women. The rate of smoking cessation success was 74% at 3 months, and there were no differences in age, spirometric indexes and associated diseases between the smoking cessation success and failure group. The rate of supplement drug usage was not different in both groups either. However, body weight, mean number of cigarette usage per day and nicotine dependence scores in the failure group were significantly higher than in the success group. In multivariate analysis, body weight and mean number of cigarette usage per day were significant. Two smokers with a depressive disorder failed the smoking cessation. Conclusion: A smoking cessation intervention program in the outpatient department of pulmonology showed a favorable success rate. More intensive interventions are needed to unfavorable groups which include the obese and heavy smokers.