The influence of geochemical processes (weathering, erosion and dilution) of Internal Dinarides to the Posavina Neogene Basin and their implication to the pollution of Sava River sediments of four sampling sites in the Eastern Posavina (Županja, Brčko, Bosanska Rača and Sremska Mitrovica) was studied. For this purpose, comparison of contents of heavy metals (Pb, Zn, Cu, Ni, Cr, Cd, As, Hg) of the Eastern Posavina sediments with local background values was performed. Sediments from two boreholes of the Lopare Basin considered as non-polluted and representative for specific geologic and hydrogeologic system were used for calculation of local background values. The aim was to assess whether observed heavy metals concentrations of four sampling sites along the Sava River represent background/natural or anthropogenic contamination. This task is performed using the geo-accumulation index and total enrichment factor. According to values of the total enrichment factor (0.25 - 0.71), the anthropogenic impact on the investigated area is quite low. The heavy metals contents in river sediments, soil and groundwater are mainly controlled by geochemical processes, particularly weathering (Chemical Proxy of Alteration value 60). The results also offer novel insights into the elevated geogenic levels of Cr and Ni in the Eastern Posavina region.