INTRODUCTION Despite comprehensive tobacco control policies being in place since 1992, smoking prevalence in Thailand has not declined since 2009, indicating a potential need for individual-level measures.This study examined factors influencing successful smoking cessation attempts in Thailand. METHODS With a case-control design, smoking cessation experiences of 284 successful (defined as having quit smoking for at least six months) and 837 unsuccessful quitters, who were all lifetime daily smokers, were compared, using sociodemographic data, smoking behaviors, and smoking cessation experiences from their last quitting attempt. Data were collected between August and December 2020. Multivariateadjusted logistic regressions were employed. RESULTS Unaided smoking cessation was the most popular method among Thais attempting to quit smoking; more than 99% of both successful and unsuccessful quitters used this method. A significantly higher proportion of successful quitters favored stopping their smoking abruptly than did unsuccessful quitters. Depending on the cessation phases (nicotine withdrawal or relapse prevention)