Preheat oven to 375F.
Thaw the crab legs if they are frozen. Using a sharp knife or a pair of a scissors, slice or cut the crab legs into halves to expose the flesh. Arrange them evenly on a baking sheet or tray.
Melt the butter in a microwave, for about 30 seconds. Add the garlic, parsley and lemon juice to the melted butter. Stir to mix well. Drizzle and spread the butter mixture on the crab. Save some for dipping.
Bake the crab legs in the oven for about 5 minutes, or until the crab legs are heated. Serve immediately with the remaining garlic lemon butter and lemon slices. Squeeze some lemon juice on the crab before eating.