Incorporation of resistance genes into existing rice (Oryza sativa L.) cultivars is a powerful strategy and is commonly applied in breeding rice resistance to blast disease [caused by Pyricularia grisea Sacc. = P. oryzae Cavara (teleomorph: Magnaporthe grisea (Hebert) Barr)]. The rice blast resistance gene, Pi-ta, originally introgressed into japonica from indica rice is important in breeding for rice blast resistance worldwide. In the southern USA, the rice cultivar Katy contains Pi-ta and is resistant to the predominant blast M. grisea races IB-49 and IC-17 and has been used as the blast resistant breeding parent. Three pairs of DNA primers specific to the dominant indica Pi-ta gene were designed to amplify the Pi-ta DNA fragments by polymerase chain reaction (PCR). PCR products amplified by these Pi-ta specific primers were cloned and sequenced. Sequence analysis confirmed the presence of the dominant indica Pi-ta allele. These Pi-ta primers were used to examine the presence of Pi-ta alleles in advanced Arkansas rice breeding lines. The Pi-ta containing rice lines, as determined by PCR analysis, were resistant to both IB-49 and IC-17 in standard pathogenicity assays. In contrast, lines lacking the Pi-ta genes failed to protect rice plants against both races IB-49 and IC-17. The presence of Pi-ta markers correlated with the Pi-ta resistance spectrum. Thus, the Pi-ta gene markers provide a basis for stacking other blast resistance genes into high yielding and good quality advanced breeding rice lines.