A new iridoid glycoside, rotunduside (1), along with four known iridoid glycosides, 10-O-p-hydroxybenzoyltheviridoside (2), 10-O-vanilloyltheviridoside (3), 6″-O-(trans-p-coumaroyl)-procumbide (4) and loganic acid (5), was isolated from the rhizomes of Cyperus rotundus L. Their chemical structures were elucidated on the basis of UV, IR, MS and NMR spectroscopic analyses. In addition, the macrophages respiratory burst (MRB) inhibitory activity of the isolated compounds was reported. Compound 2 exhibited considerable MRB inhibitory activity in the test with IC50 value of ~37 μM.