The invention concerns a method of operating a wind power installation. The wind power installation has a circuit for measuring the frequency prevailing in the electrical supply network connected to a control device for controlling operation of the wind power installation. It is proposed that the power delivered by the generator of the wind power installation to the network is increased quickly and for a short period above the currently prevailing power of the wind power installation if the network frequency of the electrical network is below the desired target frequency of the network by a predetermined frequency value.