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Objective:To investigate the potentiality of mosquitocidal activity ofGliricidia sepium(G. sepium) (Jacq.)(Leguminosae).Methods:Twenty five early third instar larvae ofAnopheles stephensi (An. stephensi) were exposed to various concentrations(50-250 ppm) and the24 hLC50 values of theG. sepium extract was determined by probit analysis.The ovicidal activity was determined againstAn. stephensi to various concentrations ranging from25-100 ppm under laboratory conditions.The eggs hatchability was assessed48 h post treatment.The pupicidal activity was determined againstAn. stephensi to various concentrations ranging from25-100 ppm.Mortality of each pupa was recorded after24 h of exposure to the extract.Results:Results pertaining to the experiment clearly revealed that ethanol extract showed significant larvicidal, ovicidal and pupicidal activity against theAn. stephensi.Larvicidal activityof ethanol extracts ofG. sepium showed maximum mortality in250 ppm concentration(96.0±2.4)%.Furthermore, theLC50 was found to be121.79 and theLC90value was recorded to be231.98 ppm.Ovicidal activity of ethanol extract was assessed by assessing the egg hatchability.Highest concentration of both solvent extracts exhibited100% ovicidal activity.Similarly, pupae exposed to different concentrations of ethanol extract were found dead with58.10% adult emergence when it was treated with25 ppm concentration.Similarly,18.36(n=30;61.20%);21.28(70.93) and27.33(91.10) pupal mortality was recorded from the experimental pupae treated with50,75 and100 ppm concentration of extracts. Three fractions have been tested for their larvicidal activity of which theFraction3 showed the LC50 andLC90 values of23.23 and40.39 ppm.With regard to the ovicidal effect fraction3 showed highest ovicidal activities than the other two fractions.Furthermore, there were no hatchability was recorded above50 ppm(100% egg mortality) in the experimental group.Statistically significant pupicidal activity was recorded from75 ppm concentration.Conclusions:From the results it can be concluded the crude extract ofG. sepiumis an excellent potential for controlling An. stephensi mosquito.It is apparent that, fraction3 possess a novel and active principle which could be responsible for those biological activities.