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Objective:To determine the mosquito larvicidal activity of leaf essential oil and their chemical constituents fromClausena anisata(C. anisata) (Willd.) Hook. f. ex Benth. against Culex quinquefasciatus, Aedes aegypti andAnopheles Stephensi.Methods:Essential oil was obtained by hydro-distillation and the chemical composition of the leaf essential oil was analyzed using gas chromatography-mass spectrometry. The mosquitoes were reared in the vector control laboratory and twenty late III instar larvae of three mosquito species were exposed to based on the wide range and narrow range tests, essential oil was tested at50, 100, 150, 200 and 250 ppm and each compound was tested at various concentration (5-75 ppm) and were assayed in the laboratory by using the protocol ofWHO 2005; the 24 hLC50 values of theC. anisata leaf essential oil and their major compounds were determined following Probit analysis.Results:The oil contained were mainly β-pinene (32.8%), sabinene(28.3%), germacrene-D (12.7%), estragole (6.4%) and linalool(5.9%). The essential oil from the leaves ofC. anisataexhibited significant larvicidal activity, with24 hLC50 values of140.96, 130.19 and119.59ppm, respectively. The five pure constituents extracted from theC. anisata leaf essential oil were also tested individually against three mosquito larvae. The LC50values of β-pinene, sabinene, germacrene-D, estragole and linalool appeared to be most effective againstAnopheles stephensi(LC50-23.17, 19.67, 16.95, 11.01, 35.17ppm) followed byAedes aegypti (LC50-27.69, 21.20,18.76, 12.70, 38.64 ppm) and Culex quinquefasciatus(LC50-32.23, 25.01, 21.28, 14.01, 42.28).Conclusions:The essential oil of C. anisata contains five major compounds and has remarkable larvicidal properties, which may be considered as a potent source for the production of natural larvicides.