We consider the application of formal, mathematical programming techniques to the problem of scheduling the crude oil supply to a refinery. The relevant key decisions include the the allocation of crude oils to refinery and portside tanks, the connection of refinery tanks to crude distillation units (CDUs), the sequence and amounts of crudes pumped from the ports to the refineries, and the details relating to discharging of tankers at the portside. These decisions are typically made over a horizon of one month. Scheduling is important for two reasons : on the one hand, the economic penalties of poor scheduling are severe, and on the other, efficient scheduling techniques will enable the exploitation of opportunities e.g. unexpected cheap cargoes on the high seas. Typical approaches to this problem are based on user-driven simulations. This paper indicates how mathematical programming techniques can be applied to such problems, and highlights the advantages of using such approaches.