There is proposed a method of forming an inflated aerofoil (1), the method comprising the steps of: forming a layered, planar pre-form (30); providing at least one stress-relieving opening (44, 45, 46, 47) through the pre-form; hot creep forming and inflating the pre-form (30) to form an intermediate aerofoil; and subsequently removing material from the intermediate aerofoil, including at least a region containing the or each stress-relieving opening (44, 45, 46, 47), to form a finished aerofoil.