Content of key nutrients and anti-nutrients of the insect-resistant transgenic rice (Btt12R) developed in Korea that contains a cryIIIA insecticidal gene was compared with those of its non-transgenic counterpart (Oryza sative L. cv. Nakdongbyeo). Grains of Btt12R, its parent cultivar, and two commercial rice plants (cv. Yeonganbyeo and Hwaseongbyeo) grown in the adjoining fields under the same environmental conditions and field management were used for this study. Among the analyzed 47 nutrients (8 proximates, 17 amino acids, 8 fatty acids, 9 minerals, and 5 vitamins) and two anti-nutrients (trypsin inhibitors and phytic acid), although the levels of 17 components differed between Nakdongbyeo and Btt12R, all of the measured values from Btt12R were within the ranges of values observed in the two typical Korean varieties and commercial rice provided by the OECD. These results confirm that the nutritional quality of rice grains was not affected by the insertion of the cryIIIA gene.