Thirty-one hybridomas producing monoclonal antibodies (MAbs) against structural proteins of RSV subgroup A (Long strain) and RSV subgroup B (Japanese wild strain) were produced and separated into three groups by their reactivities with RSV-A and RSV-B using IFA. Group I was specific to RSV-A, Group II was specific to RSV-B and group III was specific to both subgroups. Characterization of selected two MAbs from each group indicated that three MAbs recognized phosphoprotein (P) and the others recognized fusion protein (F). All of the selected MAbs were IgG1 and carried kappa light chain. These selected MAbs can be used to detect the presence of RSV from NPAs and classify them into two subgroups. The infection rates of RSV in Thai children are very low and most of them were RSV subgroup A.