Acid hydrolysis and shaking extraction methods were used to extract nine genotypes of Thai rice grains. The extracts were determined total phenolic including anthocyanin contents and antioxidant capacities using 2,2diphenyl1picrylhydrazyl and the ferric thiocyanate assays from white, red, and black rice grains. The results demonstrated that the extraction methods affectedphenolic antioxidant of rice grains. The values of insoluble phenolic compounds were significantly higher than those of soluble phenolic compounds, which was about 1.3 times. The soluble anthocyanin content of grains was low comparing to the insoluble anthocyanin content. In addition, among studied rice grains, black rice possessed the highest phenolic and anthocyanin contents as well as antioxidant capacities. These findings suggested that black rice can be further explored as a functional food.