Chelidonium majus L. (Papaveraceae) is a medicinal herb used in various traditional systems of medicine to treat ulcer, cancer, oral infection, liver disorders, chronic bronchitis, asthma, etc. Different parts of this plant contain numerous therapeutically important alkaloidal constituents such as chelidonine, chelerythrine, sanguinarine, berberine and so on. The plant and its active compounds exhibit a wide range of pharmacological activities. The plants has long history of therapeutic use in medicines without any toxic effect. Today it is one of the important components of some pharmaceutical preparations. Consumption of C. majus preparations possesses toxic effects on the liver although the effect becomes controversial with its hepatoprotective effect. Numerous active constituents of C. majus interact with various drug metabolizing enzymes that mimic possible interactions of this herb with the conventional drugs. This review provides detailed phytochemical, pharmacological and toxicological information of C. majus along with mechanisms of action of its various active compounds on different aspects of pharmacology. This review also highlights plausible drug interaction of its various active compounds and the future prospect of this herb.