Changes in physiological functionality of giant embryonic rice by germination process were investigated using 70% ethanolic extract of the rices. Physiological functionality was evaluated by determining the reducing power, phenolic compound content, GABA content, and antimutagenicity. The results showed that the order of reducing power of the non-germinated rices was Nampung giant embryonic rice>normal rice> Whachung giant embryonic rice, however, the activity was high as the order of Whachung giant embryonic rice> Nampung giant embryonic rice> normal rice by germination process. About 3-fold activity increase was observed for Whachung giant embryonic rice, while, the activity of Nampung giant embryonic rice and normal rice decreased by the same treatment. The phenolic compound content of three rice cultivars were found to be almost same levels. Germination of rice increased the content of phenolic compounds by 2.6-fo1d without any considerable changes for both Nampung giant embryonic rice and normal rice. The GABA contents was highest in Whachung giant embryonic rice, followed by Nampung giant embryonic rice, normal rice in either germination or non-germination condition. The germination increased the GABA contents by more than 2.4-fold for all rice cultivars tested. We also found an increase in the antimutagenic activity by germination process for all cultivars, where the activity was the greatest for Whachung cultivar.