The anti-influenza viral activities of six stilbenoids from the lianas of Gnetum pendulum C. Y. Cheng were evaluated with two different assays, neuraminidase (NA) activity assay and cytopathic effect (CPE) reduction assay. METHODS AND RESULTS:The NA assay results showed that all six stilbenoids exerted an NA inhibitory effect, while the CPE assay indicated that among them, isorhapontigenin (2), gnetupendin B (3), shegansu B (4), and Gnetin D 6) exhibit significant in vitro anti-influenza viral activity in MDCK cells, with IC(50) values from 0.67 to 11.99 μg/mL in comparison to the positive controls oseltamivir acid and ribavirin whose IC(50) values were 0.040 and 5.54 μg/mL, respectively.