Abstract: nrDNA ITS(ITS1-5.8S-ITS2)  regions of 20 isolates of Paecilomyces farinosus were sequenced,  and its correct ITS sequence  was obtained. The results showed that the ITS of P. farinosus reported by Korean researchers was actually that of P. tenuipes. Two unidentified Korean isolates of Paecilomyces (KACC40219 and KACC40221) were identified as P. farinosus based on molecular data. The neighbour-joining tree showed that P. farinosus is monophyletic, and the teleomorph of P. farinosus was tentatively identified as a Cordyceps species.Sequence polymorphisms of the nrDNA ITS region exist among different isolates  of P. farinosus with the same geographic origins. The molecular data proved that genetic diversity of different isolates of P. farinosus is not related to geographic origins and hosts.