Dandelion extracts inhibit influenza virus propagation. Influenza virus (A/PR/8/34 [H1N1]) (1 × 106 PFU) were inoculated in MDCK cells. After 1 h, viruses were removed. (A) MDCK cells were treated with suxiaoganmaojiaonang (0.069-4.375 mg/ml), dandelion (0.0782-5 mg/ml), ostalmivir (0.0047-0.3 mg/ml) individually. The cultures were incubated for 24 h at 37°C under 5% CO2 atm. (B) MDCK cells were treated with dandelion (1.25 mg/ml, 0.625 mg/ml) individually. The cultures were incubated for 6, 12, 24, 36 and 48 h at 37°C under 5% CO2 atm. The yield of progeny viruses in MDCK supernatants was determined by plaque titrations assay. Each concentration of drugs was assayed two times in triplicate.