〔Abstract〕 Objective To compare the efficacy of laser-activated irrigation(LAI) on the removal of smear layer with different power settings when the fiber tip in the canal entrance. Methods 48 extracted single-rooted teeth were randomly divided into 4 groups(n=12) according to the final irrigation techniques: 0.5 W LAI,1.0 W LAI,ultrasonic and needle irrigation.After the final irrigation, the teeth were split longitudinally into 2 parts and observed under a scanning electron microscope.Images were taken at the coronal, middle and apical thirds of the teeth at a magnification of 1 000×and were scored in the presence of the smear layer using the Hülsmann scoring system. Results In the coronal third, 1.0 W LAI group was significantly more effective in removing SL than the ultrasonic and needle irrigation groups(P<0.05).In the apical and middle thirds, 1.0 W LAI and ultrasonic group were comparable on the removal of the smear layer(P>0.05). 1.0 W LAI group was better than the other groups, and the difference was significant(P<0.05) Conclusion 1.0 W LAI with Er, Cr: YSGG laser in canal entrance is comparable on removal of the smear layer and is better than needle irrigation and 0.5 W LAI,and is better than ultrasonic group in the coronal third.