Blueberry Smoothie

2 cups blueberries, fresh or frozen
1 cup pineapple-orange juice
1 8-ounce container vanilla yogurt
2 teaspoons sugar
5 to 6 ice cubes

Place all ingredients except the ice cubes into a blender and blend on high until smooth.
With blender running, add two to three ice cubes at a time through center opening of lid until all ice cubes have been added. Blend well and serve.