Herbs have been used permanently as the major source of medicine. Medicinal plants are important by secondary metabolites such as Silymarin, it is a mixture of flavonoids. Silybum marianum is a safe herb, rare reactions were reported if the dosage is high. There are medical confirmations for anticarcinogenic and hepatoprotective activities of Milk thistle. Silybum marianum is used vigorously in cirrhosis, prostate, skin and breast cancer, cervical cells and kidney ailments. This review is about the Phytochemistry and Ethnomedicinal uses of Silybum marianum.