Aim: The aim of this study was to evaluate the cytotoxicity of Boswellia as a root canal sealer and compare it to four different commercial types of sealers (Endofill, AH plus, MTA fill-apex,  Endosequense). Methods: The endodontic sealers investigated in this study were Endofill, AH plus, MTA fillapex and Endo sequence and Boswellia. The sealers were mixed according to the manufacturer's instructions. For experimental boswellia sealer preparation Tricalcium silicate has been prepared by solid state reaction. the cytotoxicity test were measured for each group and the means were statistically compared. Results: both MTA Fillapex and endosequenceshowed an excellent biocompatibility to fibroblast cells over Endofill, AH plus. Conclusion: The experimental sealer based on boswellia oil -resin showed an intermediate toxicity between the tested sealers.