According to the competitive ELISA test data, new preparations of monoclonal antibodies (MAb) to respiratory syncytial virus (RSV) differed in their blocking activity and they were directed to 3 different virus epitopes. MAb 9C5 and MAb 131-2A (CDC, Atlanta) competed against each other strongly and they were directed to epitope F1a of RSV F-protein. MAbs 8C5 and 10D8 showed a two-way blocking and were presumably topologically linked. MAb 8B10 did not compete against other MAbs. The fact that MAbs 8B10, 9C5, and 10D8 may be used in indirect ELISA test to detect RSV antigens was shown. The specific activity of MAbs 9C5 was observed, by applying low antibody concentrations to ng/mg. The highest specific activity using the homologous pair MAbs-con 9C5 and 8C5 was observed in direct ELISA employing MAbs for capture and peroxidase conjugate of MAbs for detection. MAbs 8B10 were successfully used for direct (FITC-conjugate of MAbs) and indirect immunofluorescence detection of RSV antigens in the infected cell cultures and clinical materials from patients.