A method of removing excess MCrAlY overlay coating from within a cooling hole of an aluminide coated gas turbine engine component is disclosed. The method includes providing a gas turbine engine component having an internal surface (4), an outer surface (6) and a root end (8). The component also includes at least one cooling hole (10) extending from the internal surface (4) to the outer surface (6), wherein the internal surface(4) of the component is coated with a corrosion resistant aluminide coating. An MCrAlY overlay coating (12) is also located on the outer surface (6) and inside a portion of the cooling hole (10). An abrasive slurry is forced into the gas turbine engine component from the outside of the component to the inside of the component, through the cooling hole (10), such that the slurry flows through the internal surface (4) of the component and removes at least a portion of the overlay coating (12) located inside the cooling hole (10) without adversely affecting the internal surface (4) of the component. The abrasive slurry subsequently exits the component through the root end (8).