A method is provided for producing a blade, by casting, for a gas turbine. The blade includes an elongate airfoil which extends in a blade longitudinal direction, merges into a blade root at the lower end, has a shroud segment at the blade tip and is pervaded by a single cooling air channel running in the blade longitudinal direction from the blade root to the blade tip. The method includes, during the casting of the blade, the blade material being fed exclusively from the blade root into the mold provided therefor, and the cooling air channel is formed during the casting of the blade by using a single core body, which is provided, at the blade tip, with a local casting cross section increasing element.