Twenty Inter simple sequence repeat (ISSR) primers were used to assess genetic diversity of 64 Agaricus strainsincluding 45 A. bisporus strains and other 19 Agaricus spp. ISSR primers, (GA)T, (AG)YC, (GA)C and (CTC) amplified PCRpolymorphic bands between the Agaricus species or within A. bisporus strains. PCR polymorphic bands were inputted forUPGMA cluster analysis. The varieties, Saea, Saedo, Saejeong and Saeyeon that have recently been developed in Korea wereinvolved in the same group with closely genetic relationship of coefficient similarity over 0.92, whereas, other Korean strains weregenetically related to A. bisporus strains that were introduced from USA, Eroupe and Chinese. Furthermore, ISSR-PCRpolymorphism could potentially be used to identify homokaryon isolates.