Twelve URP primers were used to assess genetic characteristics of oyster mushroom including 59 Pleurotus ostreatus cultivars, two of P. florida cultivars, one P. sajor-caju cultivars, one P. abalonus cultivar and two P. eryngii cultivars registered in Korea. Six URP primers produced PCR polymorphic bands within and between the Pleurotus species. Primer URP2F produced distinct cultivar specific PCR polymorphic bands that profiled to 15 cultivar types. PCR polymorphic bands amplified by URP2F, URP6R, URP4R and URP2R were used for UPGMA cluster analysis. Fifty nine cultivars of Pleurotus ostreatus are genetically clustered into 5 groups, showing genetic similarity over 70% among them and P. abalonus, P. eryngii and P. sajor-caju, were involved in outside groups.