Background Limited study of the progression rate for patients with AS has been done in Asian population and it may differ from that in the Western population. The purpose of this study was to evaluate the rate of progression of Korean patient population. Methods We retrospectively analyzed 326 patients (182 men, age: 67짹13 years) with AS who had paired echocardiogram > 6 months (31.2짹70.6) apart from 2003 to 2008. The exclusion criteria were defined as the presence of significant other valvular disease, history of cardiac surgery. AVA was measured using the continuity equation. Severity of AS was assessed by Doppler echocardiography. The progression rate in those subjects was expressed by increase of peak aortic valve velocity per year. Results Baseline AS was mild in 207, moderate in 81, and severe in 38. There were no significant differences between the three groups in terms of age, gender, hypertension, DM, smoking, and hypercholesterolemia. The cause of AS was bicuspid in 41 patients (12.6%). Bicuspid AV was common in severe AS groups compared to other groups (P<0.001). The progression rate was more rapid in severe AS (0.28짹0.36 m/sec per year) compared to moderate (0.15짹0.24 m/sec per year) and mild AS (0.09짹0.17 m/sec per year) (P<0.001). The progression rate in bicuspid AS was significantly higher than other AS (0.23짹0.35 vs 0.11짹0.20 m/sec per year, P=0.002). The progression rate was significantly related to initial AVA (r=-0.258, P=0.001), the peak AV velocity (r=0.134, P=0.015), the mean AV gradient (r=0.268, P=0.001) and LV end-diastolic dimension (r=0.15, P=0.009). There were no correlation between smoking, hypertension, DM, hypercholesterolemia and rate of progression. Conclusion This is the first study to estimate the rate of progression in Korean AS patients. The rate of progression in Korean AS patients was slower than Western population. AS appeared to progress rapidly according to AS severity. In moderate and severe AS, more frequent and vigilant monitoring was considered.