An airfoil for a gas turbine engine comprising: pressure and suction walls (86,88) spaced apart from one another in an airfoil thickness direction, which is generally perpendicular to the airfoil chord-wise direction, and joined at leading and trailing edges (82,84) to provide an airfoil having an exterior surface that extends in a radial direction to a tip; and a tip trench provided in the tip and wrapping at least portion of the airfoil from the pressure side wall around the leading edge to the suction side wall, the tip trench provided by a recess, wherein the tip trench is provided about a perimeter of the exterior surface of the tip and extends about a portion of the tip perimeter, and the airfoil comprises a cooling passage provided between the pressure and suction walls (86,88), and cooling holes fluidly connecting the cooling passage to the tip trench, characterised in that: the tip trench is provided by a curved recess having a curved cross-sectional shape with a width in the thickness direction, the curved recess has a valley and a lip about the tip perimeter, the lip extending radially outwardly from the valley in the radial direction beyond the valley; the tip includes a terminal end that is generally flat, wherein the valley is bounded by the lip and an exterior edge of the terminal end inboard from the lip in the thickness direction, and the terminal end extends radially outward in the radial direction beyond the lip, and the cooling holes open into the valley and are provided between the terminal end and the lip. pressure and suction walls (86,88) spaced apart from one another in an airfoil thickness direction, which is generally perpendicular to the airfoil chord-wise direction, and joined at leading and trailing edges (82,84) to provide an airfoil having an exterior surface that extends in a radial direction to a tip; and a tip trench provided in the tip and wrapping at least portion of the airfoil from the pressure side wall around the leading edge to the suction side wall, the tip trench provided by a recess, wherein the tip trench is provided about a perimeter of the exterior surface of the tip and extends about a portion of the tip perimeter, and the airfoil comprises a cooling passage provided between the pressure and suction walls (86,88), and cooling holes fluidly connecting the cooling passage to the tip trench, characterised in that: the tip trench is provided by a curved recess having a curved cross-sectional shape with a width in the thickness direction, the curved recess has a valley and a lip about the tip perimeter, the lip extending radially outwardly from the valley in the radial direction beyond the valley; the tip includes a terminal end that is generally flat, wherein the valley is bounded by the lip and an exterior edge of the terminal end inboard from the lip in the thickness direction, and the terminal end extends radially outward in the radial direction beyond the lip, and the cooling holes open into the valley and are provided between the terminal end and the lip. the tip trench is provided by a curved recess having a curved cross-sectional shape with a width in the thickness direction, the curved recess has a valley and a lip about the tip perimeter, the lip extending radially outwardly from the valley in the radial direction beyond the valley; the tip includes a terminal end that is generally flat, wherein the valley is bounded by the lip and an exterior edge of the terminal end inboard from the lip in the thickness direction, and the terminal end extends radially outward in the radial direction beyond the lip, and the cooling holes open into the valley and are provided between the terminal end and the lip.