Abstract Objective To describe a simple, rapid, and sensitive HPLC method for simultaneous determination of TRP and KYNA in human serum. Design and method Samples were deproteinized by perchloric acid. KYNA was detected at 344 nm of excitation wavelength and 404 nm of emission wavelength, TRP was detected at 254 nm and 404 nm, with a total run time of 13 min per sample. Results Standard curves of 0.49 μmol/L to 196 μmol/L of TRP were linear. Inter-day and intra-day coefficient of variations were 3.31% and 4.14%, respectively. Average recovery was 104.43%. Detection limit was 0.001 μmol/L. The linearity of the assay was maintained from 1.5 nmol/L to 2093 nmol/L of KYNA. Inter-day and intra-day CVS were 3.20% and 4.27%, respectively. Average recovery was 101.19%. Detection limit was 0.05 nmol/L. Conclusion The developed HPLC method is simple, convenient and can be applied in the diagnosis of related diseases.