There were studied the possibility of isolating thiacloprid pesticide, a representative of the neonicotinoid group, which is widely used in agriculture, using traditional methods. In the practice of forensic chemistry, the methods of A.A. Vasileva and V.F. Kramarenko are widely used for the extraction of toxic substances from biological fluids in the conduct of chemical-toxicological analyzes. Thiacloprid analysis was used in practice, but no positive results were recorded. 98-27.46% was isolated. A method has been developed for the isolation of thiacloprid from biological fluids using liquid-liquid extraction and microcrystoscopy techniques.