Agaricus bitorquis is an edible white mushroom of the genus that is cultivated at high temperature(25±1oC) unlikeA. bisporus is cultivate at 16±2oC. Unlike Agaricus bisporus, an edible white A. bitorquis mushroom is cultivated at hightemperature (25±1oC). Most farmers cultivate this mushroom for a long cultivation period in Korea. For this reason, we madeheterokayons to develop a new cultivar that generate fruitbodies for short cultivation period. Over one hundred SSIs(singlespores isolates) were collected from selected A. bitorquis ASI1151 and ASI1349 strains. Seventy-three SSIs were germinated onCDA(compost dextrose agar) media after 20 days (minimum) or 83 days (maximum) incubation under different mediacondition. The mycelial growth rate of germinated SSIs was different. 9 homokaryons in ASI 1151 and 11 homokaryons in ASI1349 from SSIs were selected by OPN-02 primer in RAPD analaysis. Also this primer was used to select heterokaryon thatcross among each homokaryon with compatible locus. Therefore 44 compatible matings were confirmed of 99 crossed lines.