Background: Echocardiographic transaortic jet velocity (Vmax), mean pressure gradient (mPG), and aortic valve area (AVA) are routinely measured for severity of aortic stenosis (AS). Additionally, prolonged ejection time (ET), acceleration time (AT), and its ratio AT/ET are also known as indexes of AS severity. However, acoustic window dependency of AT/ET is not well studied. Methods: Eighty-one patients with AS assessed by transaortic jet tracing of all of three approaches (apical 3-chamber (3C), apical 5-chamber (5C), and right parasternal (R)) were included in this study. ET, AT, and AT/ET were measured on continuous Doppler recordings obtained by 3C, 5C, and R approaches. Also, ET and AT were corrected by dividing by (R-R interval)1/2, and they were named as cET and cAT. Results: No differences were observed in cET among 3 approaches. However, cAT was significantly longer in R (115+23 msec: p<0.05) compared to that of 3C (105+21 msec) or 5C (105+20 msec). AT/ET was significantly greater in R (0.340+0.058, p<0.05) compared to that of 3C (0.317+0.053) or 5C (0.316+0.055). AT/ET-peak V relation of R approach positioned significantly upward (ANCOVA, p<0.05) comparing to that of 3C or 5C. Also, AT/ET-AVAi relation of R approach positioned upward (ANCOVA, p<0.05) comparing to that of 3C or 5C. Conclusions: AT/ET by R approach was greater than that by 3C or 5C approach. Although multiple acoustic window’s approaches including R is recommended to obtain the maximal Vmax or mPG, AT/ET is better in 3C or 5C approach than R when AT/ET is used for AS severity.