Objective: Because some energy drinks have sour taste, it might erode tooth surface. This study evaluated the erosive characteristics of human teeth when exposed to some popular energy drink manufactured in Thailand. Methods: Twenty human permanent premolar teeth were divided into 4 groups (n=5). Three groups had been exposed to three different brands of energy drinks for 8 hours and the surface hardness and depth of erosion were measured from the beginning to 8 hours of exposure compared with a positive control group, carbonated drink, by using one-way ANOVA and Tukey HSD. Results: All drinks were subjected to analyzed their pH before testing and the results showed that the pH of the drinks were ranged from 2.49 to 3.55 which were less than critical pH of demineralization. One-way ANOVA showed a significant reduction in surface hardness and an increasing of erosive depth when the exposure time was increased in all groups (p<0.05). Although the surface hardness of one experimental group which possessed the lowest pH (171.07+34.60 kg/mm2) was significantly more than the others were, the erosive depths of all groups were not different. Conclusion: The energy drinks used in this study showed the effect on dental erosion as same as the control group was whereas one of the experimental groups possessed the lowest pH effect on dental erosion less than the others were.