Hemorrhagic Fever with Renal Syndrome (HFRS) has been considered a serious infectious disease in China since 1950s.The disease is in most occasions caused by Hantaan virus (HTNV) and Seoul virus (SEOV) .Although simultaneous detection of both viruses has been accomplished with RT-PCR method, the reaction is time-consuming and requires PCR amplifier, which restricts its application.Thus a rapid convenient test to simultaneously detect both viruses is in demand.In this article an assay which was based on loop-mediated isothermal amplification is demonstrated which employs only such apparatus as water bath or heat block.Two methods, a chromogenic one using calcein/Mn2 + complex and the real-time turbidity monitoring one, were used to access the process of reaction.The new method was compared with RT-PCR method in terms of sensitivity, specificity, detection limit.With the optimized reaction conditions, the detection limit of LAMP reached 10 copies/μl, which was much more sensitive than the RT-PCR method (1000 copies/μl).The specificity of LAMP-based assay was also comparable to that of the RT-PCR method.The results manifested that the LAMP assay could be used to perform simultaneous and rapid detection of HTNV and SEOV.Therefore the RT-LAMP assay could become a useful alternative in clinical diagnosis of HFRS caused by HTNV and SEOV, especially in resource-limited hospitals or rural clinics in China.