Abamectin is used for the insect and mite pests control cotton, citrus fruit, vegetables, potatoes and other crops. Abamectin is not directly used in aquatic ecosystems, but it may have adverse impact on aquatic environment. The aim of this study was to determine the acute toxicity of abamectin (insecticide) on Daphnia magna (Straus, 1820) (Cladocera, Crustacea). D. magna were obtained from the Çukurova University Fisheries Faculty Freshwater Fish Research and Application Station. In the experiment, five different concentrations and one control group have been used. Each experiment was repeated two times. In this research, the static test method of acute toxicity test was used. The experiments were conducted under laboratory conditions at 20±2 oC. The results have been estimated with the dose-response data and were fitted with a log-logistic model by using R 3.0 statistical computation environment and DRC library. The 24-h and 48-h acute LC50 values were determined. According to the results, acute toxic effects researched Abamectin, the 24 h and 48 h LC50 acute toxic lethal concentration values for D. magna were calculated to be 0.020 µgl-1 and 0.0043 µgl-1.