The purpose of this study was to compare mineral trioxide aggregate (MTA; Dentsply, Tulsa Dental, Tulsa, OK, USA), which is widely used as root-end filling material, with DiaRoot BioAggregate (DB; Innovative BioCaramix Inc, Vancouver, BC, Canada), newly developed product, by using MG63 osteoblast-like cells. MTA, DB, and Intermediate Restorative Material (IRM; Dentsply Caulk, Milford, DE, USA) were used for root-end filling material while tissue culture plastic was used for control group. Each material was mixed and, the mixtures were left to set for 24 hours. MG63 cells were seeded to each group and then they were cultured for attachment for 4 hours. Following the attachment of cells to the root-end filling material, early cellular response was observed. After another 12 hours'culture, the level of attachment between cells and material was observed and in order to identify the effect of each material to bone formation, transforming growth factor beta1 (TGFβ1) and osteocalin (OC) were estimated by using enzyme-linked immunosorbent assay (ELISA), and the amount of alkaline phosphatase (ALP) was also measured. The data were analyzed using one-way ANOVA. As a result, only at OC and the number of cells which were attached to materials, there was no statistical difference between MTA and DB. At other items, there was statistically significant difference in all groups. Although DB has not shown exactly the same cellular response like that of MTA, the number of attached cells shows that biocompatibility of the material and OC indicates bone formation rate. Therefore, if DB is used for root end filling material, it is expected to lead to similar results to MTA.