Mosquitoes are among Sudan's most devastating malaria disease vector and some other endemic diseases in the world. The aim of this study was to evaluate the larvicidal activity of ethanol extract of flowers and leaves of Azadirachta indica (Neem) on Anopheles arabiensis and Culex quinquefasciatus. The selected natural products were collected from the City of Wad Medani, Gezira State, Sudan. The bioassay was assessed using the protocol of WHO. Various concentrations of each extract was tested on the active stage (3rd and early 4th instar) larvae of the two selected mosquito species. The percentage mortalities and their corresponding doses were used to calculate R2, LC50 and LC95. The ethanol extract of A. indica leaves resulted in range of mean mortalities of 20-95% and 22-92%, respectively on A. arabiensis and C. quinquefasciatus larvae. Additionally, the LC50’s was 77.62 and 52.48 ppm, while the LC95’s was 219.46 ppm and 251.18 ppm, followed the same order of larvae. The ethanol extract of A. indica flowers showed a range of mean mortalities of 30 -97% and 32-97%, respectively on A. arabiensis and C. quinquefasciatus larvae. The LC50’s was 11.22 ppm and 25.11 ppm and the LC95’s was 41.68 ppm and 43.65 ppm, followed the same order of larvae. A. indica leaves and flower were found to have potential control measure for both Anopheles and Culex larvae, with slight degrees of toxicity. However, LC’s values and Log-Probity curve showed that, the flowers have higher larvicidal potentiality than the leaves against both larvae. Therefore, further studies should be carried out to determine the appropriate manner of application and examine the mode of action for these components.