CYP2C19 is a drug-metabolizing enzyme showing various genetic polymorphisms that may cause marked interindividual and interethnic variability in the disposition of its substrates. We assessed CYP2C19 genetic polymorphisms in a Korean population using a newly developed multiplex pyrosequencing method.A multiplex pyrosequencing method to simultaneously detect CYP2C19*2, *3, and *17 alleles was designed. We established the frequency of these CYP2C19 alleles in 271 Korean subjects using the multiplex pyrosequencing method.The results showed 100% concordance between single and multiplex pyrosequencing methods. We also validated the polymorphisms identified by pyrosequencing with direct sequencing method. The allele frequencies of CYP2C19*2, CYP2C19*3, and CYP2C19*17 were 0·284, 0·101 and 0·015 respectively. These frequencies are similar to that reported for other Asian populations including Japanese and Chinese but different from that of Caucasians and Africans.The multiplex pyrosequencing method to detect CYP2C19*2, CYP2C19*3, and CYP2C19*17 concurrently, seems to be a rapid and reliable genotyping method for the detection of important CYP2C19 genetic polymorphisms. Similar to studies conducted on other Asian populations, this study reported that in the Korean population tested, the CYP2C19*2 and CYP2C19*3 alleles were relatively frequently found, whereas the frequency of CYP2C19*17 was very low.