The research was conducted at the Department of Engineering Sciences and Technology of Sokoine University of Agriculture (SUA) to study the effect of insecticidal plant materials (neem and eucalyptus leave powder) on mortality of bruchid bettles and quality of stored beans for three months storage period. The objectives of the study were; To determine the effect of different concentrations of insecticidal plant materials on insect pests mortality in stored beans, to determine the effect of different concentrations of insecticidal plant materials on organoleptic qualities of stored beans and to determine the effect of different concentrations of insecticidal plant materials on seed viability of stored beans at different storage duration. Three rates (10, 20 and 30 g/kg) of each insecticidal plant leave powder, a synthetic insecticide (Shumba supermax dust at 0.5g/kg) and an untreated grain were used as treatments. The experiment was arranged in completely randomised design in four replications. Data collected include; Insect mortality, odour, taste and seed viability index of stored bean grains. Data collected were subjected to analysis of variance (ANOVA) using General Linear Model in SPSS computer software packages (version 16) and mean comparisons were conducted using Turkey’s (HSD) test at 5% level of significance. Results showed a significant difference in percent mortality of adult bruchids due to the effect of insecticidal plant powders. The increase of adult bruchids mortality was directly proportional with the plant powder concentration. The application of insectical plant materials had influence on organoleptic quality of stored beans. However, the insecticidal plant powder had no significant effect on seed viability when compared to the controls. It can therefore concluded that, the insecticidal plant material can be used to protect grains against bruchid damage and on stored seeds for planting. For home consumption, the treated grain should be washed thoroughly with water to remove remained residue before use.Management of Mwalimu Julius K. Nyerere University of Agriculture and Technology (MJNUAT)