Abstract:The term, phenolics has been used to describe a group of structurally diverse plant secondary metabolites. This group includes metabolites derived from the condensation of acetate units (terpenoids), those produced by the modification of aromatic amino acids (phenylpropanoids, cinnamic acid, lignin precursor, catechols and coumarins), flavonoids, isoflavonoids, and tannins. The occurrence and metabolism of phenolic substances in plants, in response to injury or invasion by pathogens, such as fungi, bacteria and viruses have already been studied. Oxidised compounds produced in plants after invasion by pathogens often show considerable biological activity and are a common mechanism of resistance to plant pathogens. The present review gives information regarding the effects of different phenolic compounds on nematode system. It is found that these compounds are involved in plant defense and hence provide resistance against nematode attack.