The biological value of a soy-corn-wheat based noodle (macaroni) prepared by the General Food Corporation was studied. The protein level of the noodle was of 20.5g%. Thirty-six Albino rats were used in this experimental. The animals were divided into sex groups of six animals each. The experimental groups were fed: a) cooked macaroni without lysine; and b) macaroni supplemented with increasing levels of L-lysine HCL. The control group received commercial casein. The protein level of the experimental diets was of 10g%. At the end of the fourth week of the experiment some rats showed a slight difference in the growth curve, specially the animals fed macaroni without lysine. However, statistical analysis did not show a significant difference. The protein efficiency ratio (PER) of the experimental groups was similar to that of the control group, but when the lysine level of the diets increased there was a corresponding increase in the PER. No significant difference was noted too. These results suggest that lysine do not improve the biological value of the noodle.