The aim of the study was to evaluate the cytotoxicity of three epoxy resin-based endodontic sealer, AH Plus, Sicura Seal and Top Seal. Direct and indirect cytotoxicity were evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay and LIVE/DEAD^® Viability/Cytotoxicity Assay on MG63 osteoblasts-like cells. Data were statistically analyzed by analysis of variance and Tukey test, setting a significance level of 5%. Both results related to direct and indirect cell viability tests showed that all groups were significantly more cytotoxic than the negative control group. The cytotoxicity activity after one week of culture showed the absence of direct cytotoxicity, while a medium rate of indirect cytotoxicity. All the three epoxy resin-based sealers (AH Plus, Top Seal and Sicura Seal) showed a medium rate of cytotoxicity on osteoblasts-like cells in vitro. No significant difference was found among the sealers analyzed.