A method of modeling transportation-inventory systems is proposed in an attempt to flexibly describe the systems in which a lot of kinds of items are ordered to transport, transported, stored at the warehouses, and delivered to the customers. The system consists of a number of "sources" and "sinks." However, the problem considered in this study is totally different from the traditional transportation problem in terms of linear programming. Firstly, any number of different kinds of items can be treated for analysis. Secondly, any size of transportation trucks can be specified to transport items for any number of the sourcesink combinations. In other words, the capacity of the transportation truck is to be specified in building a simulation model. In addition, any number of both sources and sinks can be specified as required to build a simulation model. Thirdly, the order by a sink is made toward the associated source, based on the inventory policy at the sink, and t...