In serch for a new drugs modern pharmacy increasingly returns to well known in practical therapy but not always scientifically understood world of plants and herbs. Humans use organic substances filling function in plants tissue as primary (e.g. fats, sugars, protein) and secondary metabolites (e.g. flavonoids, alkaloids, tannins). The secondary metabolites, universal group of plant compounds includes quercetin. Chemical compound biogenetically belonged to flavonoid glycosides, which role, together with the growing interest in herbal medicine is increasing. It was proved that it have antioxidant activity, reducing the risk of heart disease, arteriosclerosis, complications from vessels. It affords it brings beneficial effects for patients with restricted eyesight and prevents cataract. Quercetin and its analogues action on the development of cancer cells, which can be an important starting point for prospect new compounds of anticancer activity also seems to be interesting.This work is therefore a attempt to bring the available knowledge on quercetin, its biosynthesis, biological activity and hopes of its analogues in anticancer therapy.