The site of interest of this study is Asopos river which is located in Sterea Ellada, north of Athens, and passes through areas where 20% of total Greece industrial production takes place. The extensive installation of industries in the area near the river, and the uncontrolled disposal of industrial and agricultural wastes into the river, make the water quality of Asopos questionable. The environmental problem of Asopos river basin is known since 1969, due to the detection of high Cr (VI) concentrations in ground and river water samples with potential carcinogenic effects to human health. However, the probable occurrence of industrial and agricultural organic chemicals with unknown toxic effects has not been studied so far. To the best of our knowledge, this is the first environmental monitoring study in Greece including not only the determination of legislated compounds, but also the wide-scope screening of organic chemicals for which no occurrence data exist.