Izmit Bay is oceanographically an extension of the Marmara Sea, having a permanent two-layered water system. The upper layer originates from less saline Black Sea waters (18.0-22.0 psu), and the lower one from Mediterranean Sea waters is more saline (37.5-38.5 psu). The permanent stratification occurs at about 25 m in the Marmara Sea, however, it is highly variable in Izmir Bay. Dissolved trace metals (Fe, Mn, Pb, Cu and Cd) were measured at 4 stations (western, central, eastern, and out of the Bay) along the water column. In addition, total metal concentrations were determined in surface sediments at 21 stations. The distribution of metal (Al, Fe, Pb, Cu, Zn, Co, Cr and Cd) concentrations in both the water column and surface sediments shows the influences of anthropogenic inputs to the bay. The Mn enrichment in the lower layer water of the central and eastern basins originates from the occurring anoxic conditions after the Marmara (Izmir) earthquake.