A method of controlling the output power from a wind energy installation to a utility grid (7) having a specified nominal frequency (fN) is provided, in which the output power (P) is controlled depending on the actual grid frequency (f) in the utility grid (7) such that the output power (P) is reduced when the grid frequency (f) exceeds a predetermined value. The predetermined value is at most two per mill higher than the nominal frequency (fN) of the grid (7) and the output power (P) is reduced as soon as any increase of the grid frequency (f) above the predetermined value is detected.