MRP II controlled production systems are large in scope and generally complex in operation. Consequently the total time required to fill a customer order through procurement and production activities is very long. This study proposes a method to increase the throughput of a real MRP II controlled production system by using the data available in the system. Critical raw materials and subassemblies of a product are determined by using project scheduling techniques. A simulation model is developed by using SIMAN. Simulation experiments are performed for determining raw material safety stock quantities and production batch sizes with the objective of decreasing the time required to fill a customer order.