he Odra is the second largest river in Poland, running from the Czech Republic through a large part of Poland before entering the Baltic Sea. Its catchment area has been heavily polluted by anthropogenic emissions. Our data document an intensive anthropogenic impact on the abundance of heavy metals in bottom sediments of the middle part of the Odra. Normalized heavy metal concentrations in sediments and indices of geoaccumulation (Igeo) indicate that this area is polluted by various metals, especially mercury, cadmium and zinc. The ranges of their concentrations vary as follows: Hg 0.12-2.99 mg/kg, Cd 2.93-7.87 mg/kg, Pb 21.2-163 mg/kg, Cu 11.5-88.3 mg/kg, Zn 28.0-471 mg/kg, Cr 1.57-47.5 mg/kg, Ni 5.10-19.1 mg/kg, Fe 1493-37972 mg/kg and Mn 47.6-1242 mg/kg.