The aim of this study was to assess the level of heavy metals (Al, Cd, Cr, Cu, Fe, Mn, Ni, Pb, and Zn) contamination and enrichment in the surface sediments of the Seyhan River, which is the receiving water body of both treated and untreated municipal and industrial effluents as well as agricultural drainage waters generated within Adana, Turkey. Sediment and water samples were taken from six previously determined stations covering the downstream of the Seyhan dam during both wet and dry seasons and the samples were then analyzed for the heavy metals of concern. When both dry and wet seasons were considered, metal concentrations varied significantly within a broad range with Al, 7210-33 967 mg kg(-1) dw; Cr, 46-122 mg kg(-1) dw; Cu, 6-57 mg kg(-1) dw; Fe, 10 294-26 556 mg kg(-1) dw; Mn, 144-638 mg kg(-1) dw; Ni, 82-215 mg kg(-1) dw; Pb, 11-75 mg kg(-1) dw; Zn, 34-146 mg kg(-1) dw in the sediments while Cd was at non-detectable levels for all stations. For both seasons combined, the enrichment factor (EF) and the geo-accumulation index (I-geo) for the sediments in terms of the specified metals ranged from 0.56 to 10.36 and -2.92 to 1.56, respectively, throughout the lower Seyhan River. The sediment quality guidelines (SQG) of US-EPA suggested the sediments of the Seyhan River demonstrated "unpolluted to moderate pollution" of Cu, Pb, and Zn, "moderate to very strong pollution" of Cr and Ni. The water quality data, on the other hand, indicated very low levels of these metals suggesting that the metal content in the surface sediments were most probably originating from fine sediments transported along the river route instead of water/wastewater discharges with high metal content.