Technical Abstract: Although ionizing radiation effectively inactivates foodborne bacterial pathogens in fresh-cut fruits and vegetables, it may adversely affect product quality. In this study, the effect of calcium ascorbate (CaA) and ionizing radiation on quality of 'Gala' apple slices under modified atmosphere packaging was investigated. 'Gala' apple slices, treated with water or 7% CaA followed by either nonirradiation (0 kGy), or irradiated at 0.5 and 1.0 kGy, were stored at 10 C for 3 weeks. Irradiation did not affect titratable acidity and pH of sliced apples, however, fruit slices softened following irradiation and during storage. The decrease in firmness during storage was reduced by the CaA treatment. Although the ascorbic acid content of apple slices treated with CaA decreased rapidly during storage, the ascorbic acid content was always higher in those treated samples than in the apple slices treated with water. Irradiation decreased both L* and hue values of apple slices. Hue values decreased during the entire storage period while L* increased during the first week of storage, then decreased between 1-3 weeks of storage. CaA increased L* and hue values of apple slices, suggesting CaA reduced browning even in irradiated samples. The microflora population of apples slices was not affected by CaA, and CaA treatment did not alter the reduction in microflora by irradiation. The combination of CaA and irradiation enhanced microbial food safety while maintaining quality of fresh-cut apple slices.