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Ben Coleman and Weizhen Mao Department of Computer S ien e, College of William & Mary, Williamsburg, VA 23187-8795, USA f oleman,wmg s.wm.edu Abstra t We onsider the unrelated ma hine s heduling problem where ea h job may have a di erent proessing time on ea h ma hine. This model a urately represents systems where ea h ma hine or worker has di erent abilities. A spe ial ase of this problem is tru k s heduling in a ross-do king environment where in oming tru ks are s heduled to doors and their argo is moved to outgoing tru ks. We study two algorithms that attempt to minimize the average wait time for the general unrelated ma hine s heduling problem, a non-lookahead algorithm and a lookahead algorithm. We show by extensive simulation that the lookahead algorithm produ es s hedules that are up to 35 per ent better than the nonlookahead model.