OBJECTIVE To extablish a reverse phase HPLC method for the determination of dextromethorphan and dextrophan in human urine in different races. METHODS The urine samples were hydrolyzed by enzyme,distilled and purified by acid and alkali.Then 20μL extracted sample was directly injected into the HPLC system with Phenyl column,and fluorescence detection (ER at 280 nm,EX at 310 nm).Acetonitrile water containing 10 mmol·L^-1KH₂PO₄and 10 mmol·L^-11-hexane sulfonate-Na (51∶49，pH4.0) was used as the mobile phase.The column temperature was 25℃. RESULTS The dextromethorphan and dextrophan were seperated satisfactorily.The linear ranges of dextromethorphan and dextrophan were 0.02～2 μg·mL^-1(r=0.999 8,n=9) and 0.5～30 μg·mL^-1,respectivly.The detection limits were 0.4 and 0.8 ngl·mL^-1,respectivily. CONCLUSION The method is simple and reliable.The results shows that RP-HPLC is a good method for measuring both dextromethorphan and dextrophan in human urine in different races and for studying the phenotype of the genetic polymorphisms.