Preheat the oven to 375°F
Thaw crab legs if frozen
Rinse the crab legs
Place the crab legs in a baking dish
Add 1/2 inch of water to the dish
Cover the dish tightly with aluminum foil
Bake for 15 to 20 minutes
Check that the crab legs are heated through
Remove from the oven carefully
Serve immediately with melted butter or lemon if desired