Abstract: An antifeedant can be defined as a chemical that inhibits feeding but does not kill the insect directly;the insect often may remain on the treated plant material and possibly may die of starvation.A majority of plant families rely on secondary plant metabolites for protection from polyphagous insects.It is evident from various studies that as a result of coevolutionary presures,plants have developed increasing resistance to insect feeders.Most antifeedant secondary plant compounds fall into one of four categories:sesquiterpene lactones,isoflavonoids,quassinoids,limonoids.Although on structure/bioactivity relationships nothing concrete has been established so far,they can shed some light on the molecular processes occurring at receptor membrane level of given in sect species and thus many potent antifeedants can either be isoalated or synthesized.Antifeedant compounds may be perceived by insect either by stimulation of specialized deterrent receptors or by distortion of the normal function of nurons which perceive phagostimulating in natural environment and thus less environmental contamination,they have a very important role in IPM.Further studies on their action mechanisms,their environmental impact,structure/activity relationships,synthesis of potent antifeedants and field tests are needed to develop new environmental friendly insecticides.