Abstract: In Algeria, Culicidae are widely distributed and present during all the year.Mosquitoes are generally controlled by conventional pesticides that have secondary andharmful effects on the environment in general and public health in particular. These areencouraging the researchers to propose effective and accessible alternatives based on naturalproducts such as plant extracts. In this context, the use of naturels products and environmentallyfriendly proves to be alternative to the use of synthetic insecticides .The purpose of this studyis to evaluate the larvicidal activity of plant extracts against mosquito larvae of Culex pipiens,using a local plant Artemisia absinthium. The toxicological essays, using the plant infusion,with different concentrations 5, 7.5, 10, 15, 20 and 30 g/l, were carried out against the fourthinstar larvae of Culex pipiens. The toxicological effect was estimated by the mortality recordedthroughout the treated and following stages. The recorded Toxicity showed a dose-responserelationship; explained by the increase in mortality according to the increase of concentrationand time. The highest sensitivity of the treated larvae of (100%) was recorded using the 30 g/lconcentration of aqueous extracts against the larvae. The lethal concentrations LC 25, LC50and LC90 ,were estimated using probits analysis are respectively 6.6 g/l with a confidenceinterval of 4.4 to 9.82 g/l and 13.1 g/l with a confidence interval of 8.72 to 19.54 g/l and 23.66g/l with a confidence interval of 15.84 to 35 g/l.