This study evaluated the relationship between the genetic polymorphism in the MDR1 (exon 21) genes and the pharmacokinetics of gabapentin (GBP) in healthy Korean subjects. The healthy Koreans were genotyped with respect to MDR1 (exon 21, 30 subjects) using polymerase chain reaction-based diagnostic testing. The pharmacokinetic profile of GBP was examined. A single oral dose of 300mg GBP in a capsule was administered to the subjects and the blood samples were taken during a 24 h post-dose interval. The serum GBP concentration was measured using an HPLC-fluorescence detector system. There were no significant (P<0.05) differences between the genotypes and pharmacokinetic parameters such as $AUC_{0-1h},;AUC_{0-1.5h},;AUC_{0-{infty}},;C_{max};and;t_{1/2}$. However, there was a trend toward higher values of the absorptive phase characterized by the $AUC_{0-1h};and;AUC_{0-1.5h}$ in 2677T/A subjects. In conclusion, this study suggests that GBP may be a weak substrate for the P-glycoprotein (P-gp) transporter.