In order to clarify the distribution of the avirulence genes in Magnaporthe oryzae (Hebert) Barr \[anamorph:Pyricularia oryzae Cav.\] from South China Crop Breeding Area,6 avirulence genes including ACEI,AvrPia, AvrPik, AvrPita,AvrPizt and PWL2 in 60 isolates of M.oryzae in core and noncore regions were detected by using PCR technique.The results showed that the detection rates of the 6 avirulence genes in rice blast pathogen populations in core and non core regions were 100.00% and 96.67%,33.33% and 0.00%,100.00% and 100.00%,96.67% and 90.00%,73.33% and 100.00%,100.00% and 73.33%,respectively.All the avirulence genes existed in M. oryzae in both regions except the AvrPia gene,which was not detected in the noncore region. Among them,the AvrPik gene had the highest distribution rate of 100% in both regions,and differences of distribution rates existed for the other avirulence genes in the rice blast fungus in the two regions.