We report the detection of a virus, tentatively identified as Seoul virus (SEOV), from a rat (Rattus norvegicus) collected in the city of Zhangmu, Tibet. SEOV RNA was detected in lung tissue by reverse transcription (RT)-PCR, followed by sequencing. Serum samples collected from Zhangmu were positive for SEOV-specific antibodies (indirect fluorescent antibody test that used SEO antigen). Sequencing and phylogenetic analysis of partial L and S sequences together with serology results suggest that the Zhangmu01 hantavirus is an isolate of SEOV, that hantaviruses circulate in Tibet, and that rats may act as natural reservoirs for the virus.