Refrigeration systems are very important parts of processes below ambient temperature, because the high operating cost and very expensive compressors are involved. This paper introduces a new method for synthesizing integrated refrigeration systems, which combines mathematical optimization techniques and engineering knowledge to produce a systematic procedure capable of solving industrial problems. The major contribution of this method is in addressing the design of refrigeration cycle and heat integration simultaneously. In this approach, most of promising options, such as interevaporating, intercondensing, subcooling, aftercooling, economizing, and presaturating, are considered simultaneously and the capital implications (e.g., compressor, driver, flash drum, and heat exchangers) are addressed together with the operating cost. The method can be used to make major decisions in the conceptual design stage, such as the number of levels, temperature levels, heat transfer duties, approach temperatures of individual heat exchangers, etc. Several real industrial problems are solved using this method in reasonable CPU time in a PC computer.