Objective:To explore the larvicidal activity of Catharanthus roseus(C.roseus) leaf extract and Raeillus thuringiensis(B.thuringiensis) against the malarial vector Anopheles stephensi(An. stephensi),when being used alone or together.Methods:The larvicidal activity was assayed at various concentrations under the laboratory and field conditions.The LC_(50) and LC_(90) values of the C.roseus leaf extract were determined by probit analysis.Results:The plant extract showed larvicidal effects after 24 h of exposure;however,the highest larval mortality was found in the petroleum ether extract of C.roseus against the first to fourth instars larvae with LC_(50)=3.34,4.48, 5.90 and 8.17 g/L,respectively;B.thuringiensis against the first to fourth instars larvae with LC_(50)=1.72.1.93.2.17 and 2.42 g/L.respectively:and the combined treatment with LC_(50)=2.18.2.41. 2.76 and 3.22 g/L,respectively.No mortality was observed in the control.Conclusions:The petroleum ether extract of C.roseus extract and B.thuringiensis have potential to be used as ideal eco-friendly agents for the control of An.stephensi in vector control programs.The combined treatment with this plant crude extract and bacterial toxin has better larvicidal efficacy against An.stephensi. Objective: To explore the larvicidal activity of Catharanthus roseus (C. roseus) leaf extract and Raeillus thuringiensis (B. thuringiensis) against the malarial vector Anopheles stephensi (An. Stephensi), when being used alone or together. Methods: The larvicidal activity was assayed at various concentrations under the laboratory and field conditions. LC_ (50) and LC_ (90) values ​​of the C. roseus leaf extract were determined by probit analysis. Results: The plant extract showed larvicidal effects after 24 h of exposure; however , the highest larval mortality was found in the petroleum ether extract of C. roseus against the first to fourth instars larvae with LC_ (50) = 3.34, 4.48, 5.90 and 8.17 g / L, respectively; B. thuringiensis against the first to fourth instars larvae with LC_ (50) = 1.72.1.93.2.17 and 2.42 g / L. outlook: and the combined treatment with LC_ (50) = 2.18.2.41. 2.76 and 3.22 g / L, respectively. Numerical was observed in the control.Conclusions: The petroleum ether extract of C. roseus extract an d B.thuringiensis have potential to be used as ideal eco-friendly agents for the control of An.stephensi in vector control programs. The combined treatment with this plant crude extract and bacterial toxin has better larvicidal efficacy against An.stephensi.