The 13 major blast resistance(R) genes against Magnaporthe grisea were screened in a number of Korean rice varieties using molecular markers. Of the 98 rice varieties tested, 28 were found to contain the Pia gene originating from Japanese japonica rice genotypes. The Pib gene from BL1 and BL7 was incorporated into 39 Korean japonica varieties, whereas this same gene from the IRRI-bred indica varieties was detected in all Tongil-type varieties. We also found that 17 of the japonica varieties contained the Pii gene. The Pii gene in Korean rice varieties originates from the Korean japonica variety Nongbaeg, and Japanese japonica varieties Hitomebore, Inabawase, and Todorokiwase. The Pi5 gene, which clusters with Pii on chromosome 9, was identified only in Taebaeg. Thirty-four varieties were found to contain alleles of the resistance gene Pita or Pita-2. The Pita gene in japonica varieties was found to be inherited from the Japanese japonica genotype Shimokita, and the Pita-2 gene was from Fuji280 and Sadominori. Seventeen japonica and one Tongil-type varieties contained the Piz gene, which in the japonica varieties originates from Fukuhikari and 54BC-68. The Piz-t gene contained in three Tongil-type varieties was derived from IRRI-bred indica rice varieties. The Pi9(t) gene locus that is present in Korean japonica and Tongil-type varieties was not inherited from the original Pi9 gene from wild rice Oryza minuta. The Pik-multiple allele genes Pik, Pik-m, and Pik-p were identified in 24 of the varieties tested. In addition, the Pit gene inherited from the indica rice K59 strain was not found in any of the Korean japonica or Tongil-type varieties tested.