Plant flavonoids are a large group of naturally occurring phenylchromones found in fruits, vegetables, grains, bark, roots, stems, flowers, tea and wine. While as much as several hundred milligrams are consumed in the average western diet, much work remains to be done on the absorption, distribution, metabolism and excretion of these compounds. A variety of in vitro and in vivo experiments have shown that selected flavonoids possess antiallergic, anti-inflammatory, antiviral and antioxidant activities. Moreover, acting by several different mechanisms, particular flavonoids have been shown to exert significant anticancer activity including anticarcinogenic and prodifferentiative activities. Certain flavonoids possess potent inhibitory activity against a wide array of enzymes but of particular note is their inhibitory effects on several enzyme systems intimately connected to cell activation processes such as protein kinase C, protein tyrosine kineses, and phospholipase A 2. It has been suggested that biologically activated cells are susceptible to the modulating effects of flavonoids. The cell types that are influenced by flavonoids including mast cells, basophils, neutrophils, eosinophils, T & B Iymphocytes, macrophages, platelets, smooth muscle, hepatocytes and others. On balance, a considerable body of evidence suggests that plant flavonoids may be health- promoting, disease-preventing dietary compounds.