Background and Aim:Early childhood caries is one of the most common chronic diseases in children, affecting both oral and general health. Oral microorganisms are the most important causative agents associated with dental caries in children. The aim of this study was to compare the antimicrobial activity of common Iranian and non-Iranian children's toothpaste on the growth of four standard bacteria strains, including Streptococcus mutans, Streptococcus sanguinis, Lactobacillus acidophilus, and Enterococcus faecalis. Materials and Methods:In this study, six types of the most common Iranian and non-Iranian children toothpaste produced by different companies were prepared. Different concentrations of toothpaste were prepared according to the Clinical and Laboratory Standards Institute (CLSI) standard. The minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) of Iranian and non-Iranian children's toothpaste were measured by the microbroth dilution method at ten different concentrations.Results: For the S. mutans bacteria, the lowest MIC was found in Misswake, Vi-One, and 2080 toothpaste. In the case of S. sanguinis and L. acidophilus bacteria, the lowest MIC was related to Frice toothpaste, and for E. faecalis bacteria, the lowest MICs were found for Misswake and 2080 toothpaste. Mann-Whitney U test also revealed that the inhibitory and bactericidal activities of Iranian children's toothpaste on the studied bacteria were not significantly different from those of non-Iranian children's toothpaste. Conclusion:In general, the antimicrobial activity of Iranian children's toothpaste was higher than non-that of Iranian samples. In addition, the MIC of 2080 and Frice toothpaste in the four bacteria examined was lower than in other used toothpaste. To prevent early tooth decay in children use of these two kinds of toothpaste is recommended.