Purpose: This study aimed to evaluate the efficacy of Chitosan as root canal irrigant with Endovac irrigation system in removing smear layer of curved root canal walls using Scanning Electron Microscope (SEM). Materials and Methods: Fifty extracted human first mandibular molars were selected with curved mesiobuccal root (20º-35º). Samples were instrumented with Universal ProTaper rotary files till size F4 then divided into 2 main experimental groups according to the final rinse used; Group I: irrigated with 17 % EDTA Group II: irrigated with 0.2% chitosan acetate and control group, irrigated with sterile saline (10 samples). Each group was further subdivided into 2 subgroups according to the irrigating technique used; Subgroup A: using conventional needle irrigation and Subgroup B: using Endovac irrigation system. Samples were grooved longitudinally and smear layer was evaluated using SEM at the coronal, middle and apical root canal levels. The significance level was set at P≤ 0.05. Results: There was a statistically significant difference among the tested groups and the control group in the mean scores of smear layer at all root canal levels and no significant difference between irrigants used. Concerning the irrigating devices, there was no statistical significant difference between conventional irrigation and Endovac system at the coronal and apical root canal levels while at the middle level, 0.2% chitosan showed statistical significant difference with Endovac system subgroup than conventional irrigation
(P ≤ 0.05). Conclusion Endovac irrigation system was effective in smear layer removal from curved root canals using either 0.2% Chitosan acetate or 17 % EDTA as final
rinse.