The breeding of widely cultivated Agaricus bisporus white cultivar are difficult because of the scarcity of the biodiversity. Radioisotope mutagenesis has been applied in the breeding but not reported in Agaricus bisporus before. This paper reports the mutagenic effects on the basidiospores of Agaricus bisporus with different irradiation dosage of 60Co-γ ray. The results showed that the lethal rate of basidiospores was 50.6 % ~ 90.63 % under six irradiation dosages，and mutant isolates were different from control，and a new type of colony appeared. The 70 single spore isolates appeared new isoenzyme bands of esterase，peroxidase and polyphenol oxidase. Based on the analysis of isoenzyme，all the 70 isolates were clustered into 18 groups at 0.87 and 25 groups at 0.95 similarity level，respectively, while the three control isolates were clustered into one class. All these results showed that 60Co-γ radiation treatment may create new breeding material or new cultivar.
