One of the parameters that plays a key role in achieving deep desulfurization in gas oil hydrotreaters is the feedstock quality. This paper addresses the preliminary assessment of the deep hydrodesulfurization (HDS) of the diesel feed (straight run gas oil) produced from a new Kuwaiti heavy crude, namely Lower Fars (LF), compared to that from the conventional Kuwait Export Crude (KEC). The key properties of the two feeds with respect to the sulfur, nitrogen, and aromatic contents, distillation range, and distribution of different types of sulfur compounds were examined. Systematic experiments were conducted to compare the degree of desulfurization of both feeds at different temperatures. The gas oil feed from the heavy crude (GO-LF) that contained higher sulfur, nitrogen, and aromatics contents together with a higher concentration of sterically hindered alkyl dibenzothiophenes was more difficult to desulfurize than the gas oil feed (GO-KEC) derived from KEC. The desulfurized diesel fuel produced from the GO-LF was also poor in quality with a higher density, higher aromatics and polynuclear aromatics (PNA) contents, and a lower cetane index.