e developed Hantaanvirus ( 76-118) recombinant nucleocapsid protein( rNP ) as an antigen for Western Blotting ( WB ) to detect the antibodyVero E6 cell by Seoul virus (SR-11 ) as an antigen.Bb WB, 3 of 4 sera,butonly 1 of 4 by IFA, showed to be IgM antibody positive at the day 3 postinfection.The sera showed antibody titer of 1 :5120 by IFA and By WB.However, the sera showed a clear pattern even which was diluted from1 : 10 to 1 : 40969. The two methods were applied as the serologicalconfirmation of Hantavirus infection in 64 laboratory rats sera.By IFA,44 of 64 sera showed a strong IFA to infected Vero cell antigen, but, noneshowed a speciffc pattern by WB method.In addition, 30 of 64 sera alsoreacted with noninfected Vero cell antigen .The results demonstrated that thesensitivty and specificity of WB was suggested hiatsher than that of IFAtest. It was considered that the nonspecific immunofluorescence was theresponse to the cellular component.