Phyllanthus niruri, a typical member of family Euphorbiaceae, is a small annual herb found throughout the tropical and subtropical regions of both hemispheres. The genus Phyllanthus has been used in traditional medicine for its wide range of pharmacological activities like antimicrobial, antioxidant, anticancer, antiinflammatory, antiplasmodial, antiviral, diuretic and hepatoprotective. This review summarizes the information about morphological, biochemical, ethanobotanical, pharmacological, biological and toxicological activities with special emphasis on mechanism of anticancer activity of P. niruri. Gaps in previous studies such as taxonomic inconsistency of P. niruri, novel phytochemicals and their therapeutic properties, especially mechanisms of anticancerous activity and market products available, have been looked into and addressed. Scientific information related to 83 phytochemicals (including many novel compounds detected recently by the authors) has been provided in a very comprehensive manner. Copyright © 2017 John Wiley & Sons, Ltd.