Background: Aortic stenosis (AS) is a gradually progressive disease and it is well known that the patients (pts) with asymptomatic mild to moderate AS have a good prognosis. Nevertheless, a considerable number of these patients develop symptoms and require surgery within a short time period. We evaluated the impact of smoking on adverse clinical outcomes in pts with mild to moderate AS. Methods: A total of 221 consecutive pts who had mild to moderate AS were enrolled from January to December 2009. The patients were divided into two groups according to smoking (smoking group: n=21, non smoking group: n=200). Baseline clinical and echocardiographic characteristics were compared between two groups. Results: Baseline clinical characteristics showed that male (71.4% vs 28.0%, p<0.001) and previous coronary artery disease (CAD, 66.7% vs 38.5%, p=0.018) were higher in smoking group. Baseline echocardiographic characteristics including aortic valve peak velocity and mean pressure were similar between two groups. Two years clinical outcomes showed that coronary artery revascularization (CAR, 33.3% vs 6.5%, p=0.001) and myocardial infarction (MI, 9.5% vs 1.0%, p=0.046) were higher in smoking group. But aortic valve surgery and progression to severe AS similar between two groups. But, multivariate analysis showed that smoking was not an independent risk factor of clinical adverse events (OR 2.34, 95% CI: 0.69-7.8, p=0.167). Conclusions: In this study, smoking was associated with MI and CAR in pts with mild to moderate AS, but smoking was not associated with progression to severe AS. We assumed that smoking is conventional cardiovascular disease, but two years is short period to observe the degree of valvular progress. Therefore, long term follow up should be needed.