The virulence specialization of rice blast fungus, Magnaporthe grisea, was identified by using the supplementory rice varieties and hybrid rice combinations. Several dominant Chinese-races identi-fied using the Chinese differential varieties, such as ZA13, ZB13, ZC13, and ZC15, all could be furtherseparated into different pathotypes (subraces). The results suggested that the conventional method by using representative races to evaluate the resistance of rice varieties had its limitation.