Cut off apple top and stem side then use a mandolin slicer to slice apples into thin rounds 1/8 to 1/4 (3-6 mm) thick. Remove seeds or the entire core from apples. Remove peel if desired.
Coat sliced apples with sugar and cinnamon by tossing. Lay on dehydrator in a single layer.
Dehydrate at 135°F (57°C) for 6 to 8 hours or until completely dry and crispy.