The genetically modified (GM) rice, which expresses the insecticidal toxin modified Cry1Ac1 (mCry1Ac1) and the selectable marker phosphinothricin acetyltransferase (PAT), was developed by the Rural Development Administration in Korea. In this study, we used enzyme-linked immunosorbent assay to analyze mCry1Ac1 and PAT protein levels in GM rice. The levels of expression of both transgenes in ‘Agb0101’ (Oryza sativa L. cv. Nakdongbyeo) changed significantly over time, with the plant part, and growth stage. In leaves, mCry1Ac1 expression was the highest at the tillering stage (831 μg/gdw and 301 μg/gfw) and lowest in brown rice seeds (0.25 μg/gdw and 0.19 μg/gfw). Expression of PAT was also highest in leaves at the booting stage (97.49 μg/ gdw and 32.17 μg/gfw) and lowest in polished rice (1.02 μg/gdw and 0.78 μg/gfw). Unlike PAT protein, mCry1Ac1 was not detected in polished rice seeds. As expected, expression of mCry1Ac1 and PAT proteins was not detectable in control rice plants. In general, mCry1Ac1 and PAT levels declined steadily over the course of the plant life cycle.