This study deals with impacts of the shunt conductances associated with HVDC cables and VSC-HVDC stations on optimal operation of Multi-Terminal HVDC (MT-HVDC). In this study, for the first time, shunt conductances are integrated to HVDC Optimal Power-Flow (OPF) program that is executed at the Power Dispatch Center (PDC) of the MT-HVDC grid. With the objective of losses minimization, optimal reference operation points of the VSC-HVDC stations are derived. The operating points of the power converter stations are adjusted based on the calculations performed in the dispatch center. CIGRE DCS3 MT-HVDC grid, structured by CIGRE B4 working group, is taken as the test platform. Test results have revealed the optimum voltages and loss pattern change. Moreover, the findings are compared with the case of neglecting the shunt conductances.