Genistein is a natural compound which occurs in Asian diet, rich in soy products. It has a wide spectrum of activity, expressed both in protecting cells from malignant transformation, reducing proliferation of tumor cells and stimulating apoptosis. In the other hand, genistein also prevents from some of the side effects manifesting in menopausal estrogen deficiency also being a good research object in this field. It has been shown, among others effect of genistein on: the level of free radicals and reactive oxygen species in the body, the metabolism of carcinogenic factors, cell cycle progression, initiation of apoptosis, angiogenesis, inflammatory processes and immune response. To achieve the desired therapeutic effect it is crucial to determine genistein dose titration in order to obtain an appropriate concentration in the tissues of phytohormone and duration of therapy.