Cyperus rotundus (nut grass in English) is a perennial erect sedge plant and is distributed in over 90 countries of the world, where it has been mostly classified as a highly invasive weed. Despite this classification, the plant has been considered from traditional times to be medicinally important. The traditional uses of the plant in various countries include uses against various gastrointestinal tract disorders, skin diseases, leprosy, fever, and neurological disorders. Evaluation of the plant and especially its rhizomes in a scientific manner has revealed the presence of numerous phytochemicals and wide-ranging pharmacological activities, which include anti-microbial, gastrointestinal, wound healing, anti-diabetic, anti-cancer, anti-malarial, anti-obesity, hepatoprotective, and anti-pyretic activity. The scientific validation of a number of traditional uses strongly indicates that the plant may prove useful in the discovery of a number of lead compounds and novel drugs.