To evaluate the human risk of long-term intake of genetically modified (GM) rice, we carried out RT-PCR of housekeeping genes. Housekeeping genes, which show highly uniform expression in living organisms during various stages of development and under different environmental conditions, were normalized by RT-PCR. We assessed the expression of 10 common housekeeping genes (18s rRNA, 25S rRNA, UBC, UBQ5, UBQ10, ACT11, GAPDH, eEF-, -TUB, GAPDH, -actin, B2m, G6pd2, Gyk, Gus, Hprt, Cyclophlin A, Tfrc, -tubulin and RPL13A) in the liver, stomach, small intestine, large intestine, kidney and spleen of mice fed GM or non-GM rice. We found no significant differences in the expression of housekeeping genes between the two groups of mice.