in vivo evaluation of synergistic effect of chitosan and its combination with CHX as intracanal medicament against the resistant bacteria like E,faecalis will have important clinical implications in nonsurgical endodontiv retreatment. Hence, the aim of this clinical study is to evaluate the antimicrobial efficacy of chlorhexidine and its combination with chitosan as intracanal medicament in response to E. faecalis in retreatment cases. Materials and Methods Thirty patients between 19-65 years of age requiring root canal retreatment were selected for the study. All selected teeth were single rooted which were symptomatic or asymptomatic and had history of root canal treatment and showed periapical radiolucency upto 4mm. Ethical clearance was obtained from the institutional ethical committee. All patients were explained about the treatment procedure and informed consent was taken. The selected tooth was isolated with a rubber dam. The crown and surrounding rubber dam were disinfected with 30% hydrogen peroxide for 30s followed by vigorous swabbing of 3% sodium hypochlorite solution. Subsequently 5% sodium thiosulfate was used to inactivate the disinfectant. Access preparation was done with a sterile Endo access