The protein value of Guangdong rice fortified with lysine and threonine in different propotion by NBI was investigated.In the writer's previous experiment, the Guangdong rice protein fortified with L-lysine and DL-threonine simultaneously obtained the best result on weanling rats. This consecutive experiment was divided into two parts; 1) the further verification of the fortified protein was studied by NBI in adults rats fed diets containing rice meal enriched with 0.3% of L-lysine, 0.5% of L-lysine plus 0.3% of DL-threonine. 2) the effect of applying nonfat soybean meal with equal quantity of lysine and threonine as above instead of pure amino acids were investigated in weanling rats by NBI. The result provided that the protein of Guangdong rice fortified with 0.5% of L-lysine plus 0.3% of DL-threonine simultaneously gave the best effect on weanling and adult rats, quite similar to the egg protein. The nutritive value of soybean meal supplementation was parallel with the fortification of amino acids, although its digestibility was lower. It suggests that lysine and threonine are the main limiting factors in improving the protein quality in Guangdong rice.