The goal of this study is to carry out exergy analyses for an experimental variable-speed refrigeration system working with R404a in order to determine irreversibility rates and exergetic efficiencies of system components and the overall system. For this aim, an experimental refrigeration system was designed with a frequency inverter mounted on compressor electric motor. Controlling the rotational speed of the compressor with a frequency inverter is one of the best methods to vary the capacity of the refrigeration system. The experiments were made for different compressor electric motor frequencies. The results showed that at low-frequency values, irreversibility rates of the system decreased and exergetic efficiencies were increased. In addition, the major irreversibility occurs in the compressor by 61.47-61.83% followed by condenser by 17.00-16.52%, evaporator by 12.39-13.73% and expansion valve by 6.24-6.76% for different compressor frequencies. Copyright (C) 2009 John Wiley & Sons, Ltd.