Successful root canal treatment depends on the cleaning and disinfecting of root canal before I obturation. The study aimed to evaluate the effectiveness of Laser-activated irrigation (LAI) Er:YAG I laser with EDTA 17% and distilled water in removing the smear layer and enhancing the results of I endodontic treatment. 90 human extracted single-rooted teeth were included. Root canal preparation was done using I rotary instruments with irrigation 5.25% NaOCl. Teeth were randomized into 30 teeth in 3 groups; I the first experimental group received Er:YAG laser (a 17 mm 400-pm conical tip, 10 Hz, 0.5W, 40 I mJ) + EDTA 17% for 1 minute, the second experimental group received EDTA 17% for 1 minute I and the control group received Er:YAG laser + distilled water for 1 minute. Teeth were bisected I longitudinally, and root canal was examined in coronal, middle and apical regions for smear layer I removal by scanning electronic microscope. Data were analyzed statistically by SPSS software. The smear layer removal was higher in all regions of walls of root canal when combined EDTA I 17% with Er:YAG laser. Comparison between regions showed that smear layer removal was better I in coronal, middle regions than apical region in both groups (P<0.05) Er:YAG laser has proved its efficacy when combined with EDTA 17% in removing smear layer I and debris from the root canal surface, due to activation of the irrigant solution. © 2021. All Rights Reserved.