BACKGROUND To sequence, analyze and express the nucleotide sequences of S and M segments of hantavirus strain 84Fli. METHODS S and M segments of hantavirus 84Fli strain were amplified by RT-PCR, the PCR products were cloned into plasmid pCR2.1-TOPOr. Three clones of each segment which have been sequenced were randomly selected. The coding region of S and M segments were amplified by PCR, and cloned into expressing vector pcDNA3.0. Transient expression of nucleocapsid protein, G1 and G2 glycoproteins in COS7 cells were performed by Lipofectin transfection. The expression of NP, G1 and G2 have been conformed by using immunofluorescence, Western blot and immuno-precipitation methods. RESULTS The full length S and M segments cDNA have been amplified and cloned. The S and M segments of hantavirus strain 84Fli contained 1 688 and 3 616 nucleotides respectively. CONCLUSIONS Deduced amino acid sequences of NP and glycoproteins revealed high homologue to other Hantaan viruses. NP, G1 and G2 proteins of 84Fli can be transiently expressed in COS7 cells.