Despite the increased attention recently to material requirements planning (MRP) in the research literature. MRP has frequently proved to be unsuccessful on actual implementation. One factor related to its unsuccessful implementation is that MRP systems are often not sufficiently analysed and tested within an actual shop scenario prior to implementation. In this paper, a network simulation model that integrates the MRP-based shop control level with the shop level in a manufacturing system is described, and its usage demonstrated within the context of a realistic shop scenario that encompasses multiple-level product structures, several-component items, job and assembly operations, machine setups and backordering.