Purpose: This study sought to compare the elemental constitution, morphological characteristics, particle size distribution, biocompatibility, and mineralization potential of Ortho MTA (OMTA) and ProRoot MTA (PMTA). Materials and Methods: OMTA and PMTA were compared using energy-dispersive spectrometry, particle size analysis, and scanning electron microscopy. The biocompatibility and mineralization-related gene expression (osteonectin and osteopontin) of both MTAs were also compared using methylthiazol tetrazolium assay and reverse transcription-polymerization chain reaction analysis, respectively. The results were analyzed by Kruskal-Wallis test with Bonferroni correction. P-value of <0.05 was considered significant. Result: The morphology of OMTA powders was similar to that of PMTA. The constituent elements of both MTAs were calcium, silicon, and aluminum. The mean particle sizes of OMTA and PMTA were 4.60 and 3.34 mm, respectively. Both MTAs had equally favorable in vitro biocompatibility and affected the messenger RNA expression of osteonectin and osteopontin. Conclusion: Within the limitations of this study, OMTA could be a promising biomaterial in clinical endodontics.