1. Preheat oven to 375 degrees F.
2. Place ham on rack in large roasting pan and bake in preheated oven for 2 1/2 hours.
3. In small saucepan, over medium-high heat, cook apple jelly and cinnamon to boiling. Boil for two minutes.
4. Brush ham all over with glaze and then put back into oven to bake for 30 minutes to 1 hour, brushing ham occasionally with remaining glaze.
5. Remove ham from oven and allow it to sit and cool for 20 minutes for easy slicing.