Purpose : This study was performed to evaluate a new rapid diagnostic kit (BIOLINE $RSV^{TM}$; Standard Diagnostics Inc., Yongin, Korea), a lateral-flow immunoassay, in the detection of respiratory syncytial virus (RSV) from the nasopharyngeal aspirates (NPA) of children with lower respiratory tract infections (LRTIs) in comparison with other diagnostic methods. Methods : Three hundred and nineteen NPAs were selected from a large pool of NPAs that had been obtained from children with LRTIs. All specimens had already been tested for RSV by culture and immunofluorescent (IF) test, and had been kept frozen. Tests with BIOLINE $RSV^{TM}$ were performed at least twice. All who conducted the experiments or interpreted the test results were blinded to the results of both culture and IF tests. Results : One hundred seven (97.3%) of 110 specimens that were positive for RSV by both culture and IF test, 29 (87.9%) of 33 that were positive by IF test only, 20 (76.9%) of 26 that were positive by culture only, and 140 (93.3%) of 150 that were negative by both methods were negative for RSV by BIOLINE $RSV^{TM}$. By combining the above results, the following 5 diagnostic values of BIOLINE $RSV^{TM}$ were determined in comparison with viral culture or IF test; sensitivity, 92.3% (156/169, 95% confidence interval [CI], 87.1-97.5%); specificity, 93.3% (140/150, 95% CI, 88.4-98.2%); positive predictive value, 94.0% (156/166, 95% CI, 89.5-98.5%); negative predictive value, 91.5% (140/143, 95% CI, 86.0-97.0%); and agreement, 95.9% (306/319, 95% CI, 92.1-99.7%), respectively. Conclusion : This study revealed that BIOLINE $RSV^{TM}$ demonstrated good sensitivity and specificity for the detection of RSV antigen from NPAs of children with LRTIs. Because of simple methods and quick results, this test may be useful for the diagnosis of RSV infection during the epidemic periods.