The experiment was designed to study the effect of dietary methionine (Met) levels on duodenal flows of endogenous nitrogen (EN) and endogenous amino acids (ENAA) in growing goats fed normal protein-containing diets. Three goats with an average body weight of (20±2.5) kg were fitted with ruminal, duodenal cannulae and jugular veins polyvinyl catheters, and allocated to three dietary treatments in a 3×3 Latin square design. The dietary treatments consisted of a total mixed diet containing three levels of Met which were 0.15%, 0.25% and 0.35%, respectively. EN and ENAA were determined using isotope dilution method. The results showed that the duodenal flows of EN and ENAA were the lowest when the dietary Met level was supplemented at 0.15%, and there were no significant differences on duodenal flows of EN and ENAA (P＞0.05). In conclusion, the duodenal flows of EN and ENAA were not significantly affected by the dietary direct supplementation of Met (P＞0.05), and the isotope dilution method was relatively stable in determination of EN flow.