The primary objectives of this study are: 1) to determine the effectiveness of culturally-tailored smoking cessation decision aids by comparing the proportion of using smoking cessation medication in Korean smokers visiting primary care clinic and health screening center with control, and 2) to identify the factors associated with the decision to use the smoking cessation medication, including sociodemographic, medical, behavioral and cognitive factors, etc. The secondary objective of this study is to determine the smoking cessation rates and use of smoking cessation medication in real world setting and identify the factors associated with smoking cessation.