Four new chromone glycosides, corymbosins K1-K4 (3-6), together with two known compounds, noreugenin (1) and undulatoside A (2), were isolated from the whole plant of Knoxiacorymbosa (Rubiaceae). The structures of the new compounds were established through extensive NMR or X-ray spectroscopic analysis as 7-O-beta-D-allopyranosyl-5-hydroxy-2-methylchromone (corymbosin K1, 3), 7-O-beta-D-6-acetylglucopyranosyl-5-hydroxy-2-methylchromone (corymbosin K2, 4), 7-O-[6-O-(4-O-trans-caffeoyl-beta-D-allopyranosyl)]-beta-D-glucopyranosyl-5-hydroxy-2-methylchromone (corymbosin K3, 5) and 7-O-[6-O-(4-O-trans-feruloyl-beta-D-allopyranosyl)]-beta-D-glucopyranosyl-5-hydroxy-2- methylchromone (corymbosin K4, 6). Compounds 2-5 were subjected to test their immunomodulatory activity invitro.