Euphorbia tirucalli are reported to possess antibacterial activity against various microorganisms. This in vitro study aimed to evaluate the antibacterial properties of Euphorbia tirucalli stems extracts (methanol, ethanol and aqueous extracts) against dental caries-related bacteria, i.e. Streptococcus mutans (S. mutans) and Streptococcus sobrinus (S. sobrinus). The antibacterial properties were determined using agar-well diffusion method at different extract concentrations (10, 20 and 30 mg/ml). Commercially available amoxicillin (10 µg) was used as positive control while the appropriate solvent served as negative control. The methanolic and ethanolic extracts of Euphorbia tirucalli stem were found to be effective against S. mutans and S. sobrinus. However, the aqueous extract of Euphorbia tirucalli stem showed no activity against both bacterial strains. The differences in the antibacterial properties in different extracts of Euphorbia tirucalli may be due to the differences in phytochemical constituents.