A total of 308 isolates of Magnaporthe grisea collected from rice plants in Yunnan province, China were tested for their mating type and fertility. Of the 79 isolates for which a compatible mating type was identified, 9 isolates belonged to type A and 70 to type a. Isolates with an unknown mating type numbered 229. Mature perithecia and viable ascospores were formed in several cross-combinations by using two isolates pathogenic to rice that belonged to different mating groups. It is considered that the use of fertile rice blast isolates may enable to analyse genetically the characteristics of M. grisea.