The Osborne method comprising of a 2-step in vitro digestion of rice flour was used to extract albumin, globulin, prolamin, and glutelin by using pepsin and trypsin. Subsequently, the antioxidant activity of the resultant rice digest was studied in terms of 2,2-diphenyl-1-picrylhydrazyl (DPPH?), 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS+?) and ?OH radical scavenging as well as Fe2+-chelating activity. The results revealed that the in vitro digests of four rice proteins exhibited better antioxidant activity than commercial soybean peptides. Among these, the digest of prolamin showed the highest antioxidant activity, where the half-maximal inhibitory concentration (IC50) values of DPPH?, ABTS+?, and ?OH radical-scavenging as well as Fe2+-chelating activities were 30.88, 27.61, 5.43, and 0.18 mg/mL, respectively. The enzymatic hydrolysates of albumin, globulin, prolamin, and glutelin showed good Fe2+-chelating activities with IC50 values < 1 mg/mL. The results indicated that the in vitro digests of the four rice proteins tested in this study showed different antioxidant activities and that the molecular weights of these small peptides were in a range of 181~1000 Da, which is similar to that od antioxidant peptides that can be absorbed easily in humans.