Recently, rapid advances in single nucleotide polymorphisms (SNPs) mapping can now be applied to characterize the individual patients who suffer adverse effects to a drug, or those for whom a drug shows efficacy. The aim of this study was to identify and functionally characterize OCT2 variants as a first step towards understanding whether genetic variation in OCT2 may contribute to interindividual differences in renal elimination of vancomycin. Taiwanese patients will be screened and 12 coding region variants of OCT2 will be identified. The non-synonymous variants of OAT1, OAT3, or OCT2 will then be constructed and characterized using in vitro human renal cell models. It is to establish whether genetic variants in OAT1, OAT3, or OCT2 are likely significant contributors to intersubject variability in drug response. In addition, approaches toward the prevention of some drug-induced nephrotoxicity are discussed, base on molecular mechanisms of renal accumulation of these drugs. Perhaps our understanding of OAT1, OAT3, or OCT2 in pharmacogenomics may contribute to the goal of individualized drug therapy. Development of new strategies based on the understanding of their cellular handing may achieve safer and more effective therapy for personalized medicines.