The toxic effective of wheat grains treated with Egyptian sesban, Sesbania ae-gyptica seed extracts offered to rice weevil, Sitophilus oryzae was determined. Chlo-roform extract was found to be the most effective. Reproductive potential of treated weevil were strongly affected as number of laid eggs was reduced and no progeny were obtained when adults were fed on wheat grains treated with either Lc50 or Lc95 . Extracts treatment with Lc95 of extracts gave protection up to 10 weeks for petrole-um ether, and 9 weeks for both chloroform and acetone extracts. All tested extracts reduced grain germination at the end of 14 weeks storage period. Treated wheat grains with Egyptian Sesban seed extracts reduced the weight loss of grains infested with the rice weevil. Biochemical studies show that some enzymes were affected in treated insects. S. aegyptica acetone extract was more effective than the other ex-tracts, in this affect, as it caused a significant reduction in amylase, trehalse and acid phosphatase activity. However, this extract caused an increase in invertase, alkaline phosphatase and cholinestrase activity.