Respiratory syncytial virus (RSV) has long been considered an important cause of severe lowerrespiratory tract infection in infants and young children throughout the world. Unfortunately, noeffective treatment of RSV exists. Therefore, New agents are needed to reduce the impact of RSV.We have studied the anti-viral effect of traditional Chinese midicinal herbs for over ten years andfind Herba Patrinea (a Chinese medicinal herb) has the anti-RSV effect in vitro. In this study, theHerba Patrinea was extracted with hot water, condensed and sterilized. The cytotoxicity of theaqueous extract was tested by adding the diluted extract directly to HeLa cells and its effect onanti-RSV was estimated by the CPEI assay. As a result, the median cytotoxic concentration (CC50)of Herba Patrinea was 32mg/ml by morphological observation, the median effective concentration (50%effective concentration, EC50) of the Herba Patrinea against replication of the Long strain of RSVin HeLa cells were 1.25mg/ml. The selectivity index (SI=CC50/EC50) is 25.6. Moreover, HerbaPatrinea gave a dose-dependent response in inhibiting RSV. In time of addition experiment,Herba Patrinea inhibited replication of RSV in HeLa cells when it was added at 0h, 2h, and 4hafter virus infection. In summary, the results of this study suggest Herba Patrinea may be a novelanti-RSV drug and it is worthy of further studying.