The purpose of this paper is to show the importance of economic optimization of large capacity or industrial refrigeration systems and to present the results and conclusions obtained by a computer software which was developed specifically to determine the economic optimum values of the design parameters of refrigeration systems. Both liquid chillers and groups of cold storage rooms operating at various levels of low temperatures are covered. Various case studies and sensitivity analyses have been performed to provide specific numerical examples and to determine the effects of certain parameters. It was found that condenser type, ambient temperature, yearly operating hours, electricity price, real interest rate and refrigerant are the most important parameters in the economic optimum design of refrigeration systems.