<jats:title>Abstract</jats:title><jats:p>Two new sesquiterpenes, epi‐guaidiol A (1) and sugebiol (3), together with four known sesquiterpenes, guaidiol A(2), sugetriol triacetate (4), cyperenoic acid (5), and cyperotundone (6) were isolated from the rhizomes of <jats:italic>Cyperus rotundus</jats:italic> L. Their structures were identified by MS and NMR experiments, and the complete assignments of <jats:sup>1</jats:sup>H and <jats:sup>13</jats:sup>C NMR data for two new sesquiterpenes were obtained by the aid of two‐dimensional (2D) NMR techniques, including HSQC, HMBC, <jats:sup>1</jats:sup>H‐<jats:sup>1</jats:sup>HCOSY and nuclear overhauser enhancement spectroscopy(NOESY). Copyright © 2009 John Wiley & Sons, Ltd.