Herbicides, such as 2,4-dichlorophenoxyacetic acid (2,4-D) and chlorsulfuron, are widely used in agricultural areas. In this study, residues of these herbicides were analysed in soil and in earthworms, which are described in ecotoxicological studies as indicator organisms, in agricultural areas in and around Istanbul using the HPLC method. In the field investigations, a wheat field in the I.U. Veterinary Faculty Farm was treated with 2,4-D herbicide at a dose of 200 cc/da. Following this application, soil samples were collected at 1-week intervals in order to determine herbicide's persistence in the soil. 2,4-D was totally dissipated in the wheat field by the end of the 4(th) week. Subsequent field samples were collected in the form of soil and earthworm from the villages of Hadimkoy, Buyukcekmece Karaagac, Buyukcekmece Tepecik, Catalca and Catalca Incegiz. Two different methods were used for soil and earthworms. With the modification of these two selected methods, detection of both herbicides together (2,4-D and chlorsulfuron) was achieved. It was observed that both herbicides accumulated in earthworms.