The paper discusses the simulation of Non-azeotropic Refrigerant Mixtures (NARMs) for use in a dual-circuit refrigerator/freezer (RF) with countercurrent heat exchangers. The simulated RF has two complete and independent refrigeration cycles for its two compartments. It uses a NARM in each cycle and countercurrent heat exchangers throughout. In a standard cabinet, the RF is simulated to provide energy savings of 24 percent compared to current U.S. RF designs. The NARMs modeled with the best performance are R-32/-152a, R-32/-142b, and R-22/-142b. An 18 percent improvement can be expected from the dual-circuit system using R-12 alone, and an additional 6 percent improvement can be gained by replacing R-12 with the selected NARMs in countercurrent heat exchangers. Advantages of the system include greatly reduced energy consumption, easy temperature and humidity control for each compartment, no humidity or odors transferred between compartments, and increased time between defrost cycles. Disadvantages include additional hardware requirements, compressor size, and the difficulties of using a NARM.