The development of truck dispatching systems has during recent years taken two directions. One has been systems using mathematical optimization and powerful computers. These systems also accomplish production planning and can take into account desired blending of the ore. The other direction has been systems which are based on decision rules and which use micro computers. Such systems are less costly than the optimizing systems and easier to use. We propose now to combine the advantages of these two approaches of truck dispatching systems: an optimizing system on a micro computer. This paper presents the organization of the system, the optimization procedures used for the equipment planning, the operational planning and the actual dispatching. Also presented are comparisons by simulation of an optimizing system with an other dispatch procedure, as well as operational results of 6 months of the Mount Wright of Québec Cartier Mining Co.