ATP-binding cassette (ABC) transporters participate in drug disposition and response in various conditions, and many polymorphisms in ABC transporter genes have been recognized in association with altered transporter functions of various drugs. Studies on epilepsy have focused on the C3435T polymorphism of the ABCB1 gene, but other ABC transporters are also thought to be involved in the transport of antiepileptic drugs. We have evaluated the functional polymorphisms of ABCB1, ABCG2, and ABCC2 genes with regard to epilepsy drug response in partial epilepsy, and have investigated the potential of combined effects of polymorphisms in more than one transporter gene. We studied 6 genetic polymorphisms in 3 transporter genes in 193 drug responders and 198 nonresponders. There was no significant difference between the two groups, and we did not observe any combined effects of ABCB1 and ABCG2 genetic polymorphisms. Our study suggests that genetic polymorphisms in ABC transporters may not be significant predictors of drug response in epilepsy patients.