Loading of cytosolic nitrite into the chloroplast in nitrate assimilation of rice was modified by introducing a gene for chloroplastic nitrite transport from cucumber. Rice (Oryza sativa L. japonica cv. Nipponbare) was transformed with a cDNA (CsNitr1-L) that encodes a nitrite transporter of cucumber under the control of the CaMV35S promoter. CsNitr1-L transgenic rice grown by hydroponics with nitrate supplied as the sole nitrogen source grew as well as plants grown with ammonia. In contrast the growth of the untransformed or mock-transformed control rice was retarded on a nitrate-containing medium by about 60% compared to plants grown with ammonia. Nitrite was not beneficial to the growth of the untransformed or mock-transformed control rice but sustained that of CsNitr1-L transgenic rice. Low steady-state concentration of nitrite in leaves as well as delayed non-photochemical quenching of chlorophyll fluorescence in CsNitr1-L transgenic rice seems indicative of higher nitrite use in chloroplasts.