Induction of mutation using gamma rays for improving of Mira-1 rice variety has been conducted. Rice mutant lines M2 generation have been obtained from mutation by the doses of 25, 50, 75, 100, 150 and 200 Gy of gamma rays. Selection of mutant lines tolerant to the disease was only observed in the fi eld neither genetically. Marker assisted selection is a tool to obtain a new rice variety tolerant to the disease of bacterial leaf blight (BLB) genetically. Xanthomonas oryzae pv.oryzae (Xa) was the pathogen of BLB, and the identifi cation of rice mutant lines which were containing of Xa5, Xa13 and Xa21 genes have been done using Polymerase Chain Reaction ( PCR ) method. The result showed that one mutant line, and four mutant lines from mutation by the doses of 25 Gy and 150 Gy were containing Xa5, Xa13 and Xa21 genes the same as that of Code rice variety as positive control, and none in Kencana Bali rice variety as negative control. Mira-1 rice variety as the parent plant was only contains Xa5 and Xa21 genes. The doses of 50 Gy and 100 Gy were very affective on removing of all bands for identifi cation of those genes. The purpose of this research was to obtain the mutant lines which were contain of those Xa genes as indicator for resistant to BLB disease genetically.