Objectives: To investigate the effect of commercially available hard seltzer on the tooth enamel surface. Methods: Some commercially available hard seltzer were purchased at the market and the characteristics of the beverages were surveyed. Subsequently, Cloud hard seltzer mango was selected for the hard seltzer group (group 4), Jeju Samdasoo for the mineral water group (group 1), Coca-Cola for the cola group (group 2), and Cloud Original for the beer group (group 3). The specimens were immersed in the experimental beverage for 30 minutes, then the surface microhardness and surface condition of the specimens were evaluated. Results: The average pH of the twelve types of hard seltzer in this study were 3.51±0.01 (before stirring) and 3.46±0.01 (after stirring). The pH of experimental beverage were 7.92±0.03 (group 1),2.55±0.01 (group 2), 4.41±0.01 (group 3), and 3.31±0.01 (group 4). Paired t-test of the surface microhardness of enamel before and after beverage immersion found no significant difference ingroup 1 (P>0.05), but a significant difference was observed in groups 2, 3, and 4 (P<0.05). One way ANOVA of the surface microhardness change values (?VHN, before - after immersion) amonggroups found a statistically significant difference between groups 1 and 3 (9.20±34....