To accurately calculate the protein requirements in Chinese young adults using the indicator amino acid oxidation technique. Nine women and ten men received a restricted daily level of protein intake (0.75, 0.82, 0.89, 0.97, and 1.05 g/kg), along with L-[1- 13 C]-leucine. Subjects' protein requirement was determined by a biphasic linear regression crossover analysis of F 13 CO 2 data. In doing so, a breakpoint at the minimal rate of appearance of 13 CO 2 expiration specific to each level of dietary protein was identified. This trial was registered with the Chinese clinical trial registry as ChiCTR-ONC-11001407. The Estimated Average Requirement (EAR) and the Recommended Nutrient Intake (RNI) of protein for healthy Chinese young adults were determined to be 0.87 and 0.98 g/(kg·d), respectively, based on the indicator amino acid oxidation technique. The EAR and RNI of mixed protein are 5% and 16% that are lower than the current proposed EAR and RNI (0.92 and 1.16 g/(kg·d), respectively), as determined by the nitrogen balance method. The respective EAR and RNI recommendations of 0.87 and 0.98 g/(kg·d) of mixed protein are estimated to be reasonable and suitable for Chinese young adults.