Preheat the oven to 250°F.
Toss the pumpkin seeds with the melted butter, salt and Worcestershire sauce.
Spread them evenly in a greased foil-lined 15x10x1-inch baking pan.
Bake for 45 minutes, stirring occasionally.
Increase the oven setting to 325°.
Bake until the pumpkin seeds are dry and lightly browned, about five minutes.
Serve warm or at room temperature.
