Abstract: Objective To investigate the genetic subtype and distribution of Seoul hahta virus in Liaoning province.Methods Rat lung samples and serum samples of the patients were collected in major epidemic areas and hantavirus antigens in the rat lungs were detected by indirect immunofluorescence assay.Partial M and S segments were amplified by nested reverse-transcription polymerase chain reaction(RT-PCR)using hantavirus specific primer and then sequenced, analyzed and compared with known sequences.The phyologenetic trees were constructed to analyze subtypes and geographical distribution.Results The Seoul hanta virus(SEOV)were carried by Rattus norvegicus in Liaoning province. The analytic results of partial M and S segments carried by rat lungs and patients indicated that the homology and variation of SEOV were high.The homology of nucleotides sequence was above 98.8% for samples from similar geographical areas,with a high homology for adjacent geographical areas.Conclusion The popular SEOV is S3 subtypes in Liaoning province and the gene subtypes distribution is single.