Several studies have reported the on dental erosive potential of sports drinks with a low pH. Therefore, there is a need for new components that can reduce the erosive potential of a sports drink. Hydroxyapatites (HA) are the major components of dental enamel and bone mineral as biological apatites. In addition, HA contains a significant amount of calcium and phosphate, which can promote remineralization. Hence, some remineralization of the enamel surface can be expected if nano-sized hydroxyapatite (nano-HA) is added to a sports drink. The aim of this study was to evaluate the remineralization effects of sports drinks containing nano-HA in vitro. The crowns of extracted human molars were embedded in acrylic resin and then ground flat and polished. A commercially available sports drink (Powerade, Coca-Cola, South Korea) was purchased from a local supermarket. Nano-HA was added at a concentration of 0.05%, 0.25%, and 0.5%. Deionized water (DW) was used as the negative control. The pH of each solution was measured by a pH-meter at room temperature. The enamel specimens were immersed in each solution for 15 and 30 minutes at 37°C. In order to evaluate remineralization effect, the VHN of the enamel surface was measured at every step by microhardness test (JTTOSHI INC, Japan). CLSM and SEM were utilized to identify the change of enamel surface. The pH of test solutions and VHN of enamel surface increased in proportion to the nano-HA concentrations (P<0.05). The nano-HA could reduce the erosive potential of a sports drink in a concentration dependent manner. These effects were confirmed by the CLSM and SEM images, which showed the remineralization effect of nano-HA. However, more study will be needed to examine the optimal concentration and remineralization mechanism of the nano-HA in sports drinks. In conclusion, the addition of nano-HA to a sports drink can promote enamel remineralization.