Objective To investigate on influence of CYP2D6 genetic polymorphism on pharmacokinetics of tramadol in Chinese volunteers.Methods Adult healthy Chinese volunteers with different CYP2D6 genotypes were categorized into the following four groups: group 1:CYP2D6 * 2W * 10W, group 2:CYP2D6 * 2M * 10W, group 3:CYP2D6 * 2M * 10H, group 4 : CYP2D6 * 2M * 10M. After oral ad-ministration of 100 mg tramadol, plasma and urine samples were col-lected from each subject at different time within 32 h. The plasma and urine concentrations of tramadol and its metabolite O - desmethyltramad-ol (M1) were determined by HPLC with fluorescence detection. Re-suits The main pharmacokinetic parameters of tramadol and M, in group 2 were not significantly different from those in group 1. There are significant difference for the main pharmacokinetic parameters of tram-adol and M1 between group 3 and group 1, group 4 and group 1, group 4 and group 3, respectively (P<0.05 ). Conclusion The present re-sults shown that CYP2D6 * 2 has no influence on the pharmacokinetics of tramadol, but CYP2D6 * 10 reduces CYP2D6 activity which leads to the change of phenotype, and the homozygotes has more significant in-fluence on the pharmacokinetics of tramadol than the heterozygotes in Chinese population.