For years, companies’ management has been turning to proven techniques and tools to achieve even higher productivity. They hope for, if possible, all-inclusive, easy and efficient procedures to manage their production systems. In principle, this applies to all organizations, regardless of the sector or the company focus. Especially in industrial enterprises with different machines and equipment for production processes, the quantitative indicator "Overall Equipment Effectiveness" (OEE) has been used as a key indicator to monitor their efficiency and process performance in recent years. This indicator provides relatively simple information about the possibilities and utilization of machines and equipment as well as the quality achieved in the production processes. If the OEE indicator is determined correctly based on the available and correct data in a system, the processes can be better controlled, managed and improved. However, it is important to properly monitor (decode) the data and to understand them. The paper presents the potential but also the limits (obstacles) of Overall Equipment Effectiveness (OEE) on case studies in selected domestic enterprises in the Moravian-Silesian region.