Cyperus rotundus L. (Nutgrass, family Cyperaceae) is a notorious weed which is widespread in temperate tropical and subtropical regions of the world. Owing to its richness and potent pharmacological activities, efforts have been devoted to identify its bioactive constituents. Since 1965, a total of about 192 compounds including terpenoids, flavonoids, stilbenes, aromatics and aliphatic fatty acids have been characterized. This review summarizes the bioactivities and mechanism of action of some of the compounds from C. rotundus L.