In recent times, while markets are reaching their saturation limits and customers are becoming more demanding, a paradigm shift has been taking place from mass production to mass- customized production (MCP). The concept of mass customization (MC) focuses on satisfying a customer's unique needs with the help of new technologies such as Internet, digital product realization, and re-configurable production facilities. In MC the needs of an individual customer are translated into design, accordingly produced, and delivered to the customer. In this research three hypothesis related to MCP are investigated by the data/information collected from ten companies, which are engaged in MCP. These three hypothesis are (1) mass-customized production systems can be classified into make-to-stock MCP, assemble-to-order MCP, make-to-order MCP, engineer-to-order MC, and develop-to-order MCP, (2) in mass-customized production systems the process of customization eliminates customer sacrifice, and (3) mass-customized production systems can deliver products at mass-production cost. The preliminary study indicates that while the first hypothesis is valid, MCP companies rarely fulfill what is stated in the other two hypotheses.