The purpose of this study was to examine theeffects of fifth-grade mathematics teachers’ efficacy (MTE) on their students’mathematics self-efficacy (SMSE) and mathematical achievement (SMA) inclassrooms. Two mathematics efficacyinstruments were administered to 58 classes (i.e. 58 teachers and 1244fifth-graders respectively) to gather data associated with SMA scores inschool. Statistical analyses wereapplied to the obtained data. Thefindings revealed that MTE beliefs significantly influenced both SMSE and SMA. Additionally, SMSE had a mediative impact onthe effect of MTE on SMA. Subsequent toa discussion of the findings, suggestions were proposed for further improvementof mathematics teachers’ efficacy and, in turn, for enhancing fifth-graders’mathematics self-efficacy and mathematical achievement in the future.