Stellaria nemorum L. and S. holostea L. (Caryophyllaceae) were investigated for their flavonoids. The new flavonoid 6-C-[(α-arabinopyranosyl)-( 1-->2)-O-β- xylopyranosyl]apigenin (1) and the four known C-glycosides, 6-C-[(α-arabinopyranosyl)-(1-->2)-O-β-glucopyranosyl]apigenin (2), apigenin 6-C-β- galactopyranoside-8-C-β-glucopyranoside (3), apigenin 6-C-β-glucopyranoside-8-C-α-arabinopyranoside (4), and apigenin 6-C-β-glucopyranoside-8-C-β- xylopyranoside (5) were isolated from the aerial parts of S. nemorum for the first time. Furthemore, five known flavonoids, 3,5,7-trihydroxy-3',5'- dimethoxyflavone (9), diosmetin 6-C-β-glucopyranoside (8), schaftoside (4), isoorientin (6) and orientin (7) were obtained from the aerial parts of S. holostea. Compounds 4, 8 and 9 are reported for the first time from this species. The structures of all isolated compounds were unambiguously elucidated by one- and two- dimensional NMR and mass spectral analysis, by acid hydrolysis, as well as by comparison with literature data. The crude extracts of the investigated species exhibited antimicrobial activity against Staphylococcus aureus, while none of the isolated compounds was found to be active.