Abstract: Flavonoids are phytochemicals derived from plants. They are naturally occurring plants secondary metabolites. They have been divided in several sub classes. They have many biological effects like anti-inflammation, antioxidation, antimicrobial activity, antiallergic, protection against hydrogen peroxide, antibacterial, antimalarial, anti tumor, anti cancer and immunomodulation . The total flavonoid contents varied significantly among medicinal plant, fruits and vegetables. They are involved in plants pigmentation.