The use of neurotoxic pesticides presents an environmental risk because of their impact on 11011-target species. Despite the fact that behavioral alteration is directly targeted by these molecules, few ecotoxicological tests include behavioral endpoints. In this the­ sis, one of the objectives was to develop an 8-day method to demonstrate behavioral alterations of organophosphate pesticide exposure, as well as physiological and morpho­ logical alterations in X. laevis larvae, a model amphibian species. For this, we used two model molecules, diazinon (DZN) and chlorpyrifos (CPF). The second objective was to test the physiological, morphological and behavioral alterations of an exposure to DZN, throughout the metamorphosis. After metamorphosis, the protocol included keeping all individuals in uncontaminated environment in order to demonstrate potential delayed effects of exposure. The results of the 8-day test showed a strong inhibition of acetyl­ cholinesterase activity by DZN and CPF. A decrease in the size of the individuals as well as the growth rate over 96h were also observed. In a second analysis, we were also able to show an alteration of the locomotor capacities. The complete analysis shows the capac­ ity of this new method to highlight behavioral alterations, accompanied by physiological and morphological changes that can serve as a mechanistic link. The last experiment on metamorphosis had unfortunately to be stopped at day 44 because of the presence of scoliosis in many larvae. Despite this, the analysis of early larval stages allowed us to show an influence of the developmental stage on locomotor abilities. But surprisingly, no alteration of behavior was observed at day 16. The study of developmental stages at day 44, on the other hand, suggest a delayed development in individuals exposed to the highest concentration of DZN.