Chemical investigation of the aerial parts of Gynostemma laxum (Wall.) Cogn. (Cucurbitaceae) collected in Hoa Binh province, Vietnam led to the isolation of four flavonoids: 3,5-dihydroxy-4',7-dimethoxyflavone (4',7-dimethoxy kaempferol), quercetin, ombuin, ombuoside. Their structures were determined on the basis of the IR, MS, NMR spectra and comparison with the reported data. 4',7-dimethoxy kaempferol and ombuoside (ombuin 3-rutinosid) are reported from Gynostemma laxum for the first time.