Background : Native oak tree species dominated the deciduous forests of South Korea. The acorns of them represent the main food source for wildlife species as well as human being, and they have 28 species. We analyzed and compared to the antioxidants including total phenolics and functional nutrients components among the acorns of nine kinds of oak trees (Quercus acutissima, Q. aliena, Q. mongolica, Q. variabilis, Q. serrata, Q, palustris, Q. rubra, Q. glauca, and Q. acuta). Methods and Results : Acorns were collected from each tree species, which were grown in a seed orchard. Contents of both total phenolic content (TPC) in acorns of Q. serrata were higher than others. Interestingly, Q. serrata contained the highest amount of water soluble tannins and the lowest levels of water insoluble tannins among 9 oak species, resulting that acorns of Q. serrata had the lowest proportion of insoluble tannins. Among 9 oak species tested, Q. aliena acorns contained the highest levels of total flavonoids content (TFC). Conclusion : Our result showed that nutritional composition of acorns was significantly different between oak species, indicating that tastes or nutritional values might be different as well among major oak species in Korea.