This study aims to determine the concentrations of some heavy metals that are present in the crude oil and in liquid waste of the crude oil desalting unit .The extraction method (liquid-solid) is used for concentrating and extraction these compounds from the saltwater samples .Samples were collected from the unit’s discharging points and from the subsequent treatment stages .A suitable analytical method was used to extract these metals from both of crude oil and the oil refineries᾿ liquid wastes. The objective of this study is to observe the fate of these wastes from the discharging points of desalting unit and through physical – chemical – biological treatment stages and dawn to the receiving water (Mediterranean sea). The results showed that Syrian crude oil contains a combination of heavy metals which includes : (Vanadium – Nickel – Iron – Zinc – Manganese – Copper – Cadmium – Lead - Chromium and Cobalt) .Vanadium showed the highest concentration followed by Nickel and Iron subsequently ,the total efficiency of the treatment plant achieved the following efficiencies : 41.06% (Vanadium), 44.92% (Nickel) and 39.34% ( Iron) ,then the concentration of these discharges where compared with those in marine system to show the possible adverse effects of these compounds on the surrounding biosphere.