Even though a walk-in freezer using R404A shows a good performance at low temperatures, the refrigerant R404A will be regulated by 2020 due to high GWP. Therefore, walk-in freezers using alternative refrigerants with lower GWP are to be developed. In this study, the performance characteristics of the walk-in freezers using R404A and R449A are investigated analytically according to the AHRI 1251 standard condition, which is the American standard for walk-in freezers. Based on the analysis, the walk-in freezer using R449A shows higher COP and AWEF than that using R404A.