The effects of electrodialysis (ED) alone or ED plus ultrafiltration (UF) on deacidification of mandarin orange juice were studied by using a commercial ED stack with ion exchange membranes. ED processing, reduced the total acidity of the juices by 30% (0.6~0.7% as total acidity) after 50 min and by about 60~70% (0.23~0.4% as total acidity) after 100 min, as compared to the control juice. However, the acidity reduction after 50 min of ED was determined to be suitable, when considering total acidity (0.6~0.7%, w/w) and current efficiency. There was no color change in the juices following ED, and the pH and Brix were only slightly decreased. Furthermore, ascorbic acid and citric acid concentrations showed only minor decreases, and amino-N, free sugar, and flavonoid contents remained almost unchanged. Therefore, we concluded that the nutritional integrity of the juice was maintained. ED combined with UF may be effective, not only in preventing membrane fouling, but also in preserving the nutrients, such as ascorbic acid, in citrus juice.