Genistein recognized as phytoestrogens is one of the most extensively studied isoflavones. It comprises of significant portion of Asian diet including Japanese and Chinese cuisine in the form of Soy food products. Evidence showed that geinstein increases osteoblasts formation as well as decreases osteoclast production. It plays an important role in immunity; such as suppression of delayed hypersensitivity and increases host resistance to B16F10 tumor by proliferating cytotoxic T and NK cells. It also decreases the activity of lipoprotein lipase which in turn inhibits lipogenesis and prevents the uptake of glucose in type 2 diabetic in rats. Geinstein play important role in reproductive system where it regulates the productive of oestrogen and progesterone. Moreover Geinstein has the ability to inhibit the tumor and cancer cell proliferation. Numerous beneficial effect of Geinstein including cancer treatment and function in immunity, obesity, diabetes and reproductivity Geinstein proves the potentiality of phytoestrogens as a source of bioactive substance.