The ovicidal activity was determined against eggs of mosquito Cx. pipiens after 24 h of exposure to 5 concentrations of Azadirachtin ( 0.125 , 0.250 , 0.500, 0.750 and 1mg/L) and 5 concentrations ( 5, 7.5, 12.5 ,25 ,50 µg/L ) of B.t.i. The results indicated high reduction in percentage of egg hatch resulted from treated eggs by azadirachtin, estimated by 31.41% at 1mg /L and 91.51% at 0.125 mg /L, the obtained results show a high mortality with the increase in the concentration, and prolongation in larval and pupal developments resulted from treated eggs by azadirachtin, estimated by 4.55 days at 0.125mg/L and 7.66 days at 1 mg/L in first stage, larval and pupal duration increased with the increase in the concentration of azadirachtin. The results indicated high augmentation in the percentages of the malformations with the decrease in the concentration of azadirachtin. In contrast, in adult stage, the results indicated high reduction in total eggs laid, percentage of hatchability and longevity. No effect was observed after treated eggs by B.t.i. The present study clearly showed Azadirachtin as a pontential biopesticide to control the egg stage of mosquito Culex pipiens.