Background and Objective: The previous study of Vernonia cinerea (VC) for smoking cessation shown that VC group trended to produce higher continuous abstinence rate (CAR) than placebo group but not reach statistical significance due probably to the relatively small number of participants.This study aimed to verify the efficacy of VC for smoking cessation. Methods: The study was a randomized, double-blind, placebo, controlled trial. Smoking patients were randomized by mixed-block randomization, the treatment group (N=90) received 2-gram of infusion tea bag of VC (6g/day) for 14 days ; the control group (N=82) received placebo. Outcomes was CAR which confirmed by end expiratory carbon monoxide at weeks 2,4,8,12,16 and 24.Result: The 24-week CAR in experimental group were not higher than the control group (OR,0.91;95% confidence interval, 0.18 to 4.63; p=0.91)Conclusion: There was no statistically significant differences in 24-week CAR between VC and placebo group.