Objectives:
Running a business effectively requires ensuring continuity and regularity of the activity. For this purpose, it is important to effectively and rationally manage inventories and maintain them at various levels of optimality.

Material and methods:
In the paper a design of the probabilistic model of reserves is discussed. The objective was an elaboration of the optimal strategy of materials reserves management in the series manufacturing.

Results:
The model has been verified at an attainable scale using the numerical data concerning different assortment of materials in the serial production of furniture. The proposed probabilistic model makes it possible to elaborate the optimal strategy of type R, Z in the management of reserves of based materials of the manufacturing company with large-lot production. The strategy is based on minimal expenses connected with a supply of materials.

Conclusions:
For each company to provide good quality services, it is necessary for individual, cooperating enterprises to function efficiently. The so-called "supply chain" is a specific sequence of activities enabling the satisfaction of market demand for a given product. The supply chain consists of companies and plants that are involved in supplying raw materials, processing them into semi-finished products and, ultimately, creating a finished product. The simplest supply chain consists of a company, suppliers and customers. However, it is good to know that many more companies are involved in most production processes, including transport, logistics, finance and IT.