A method for controlling the injection quantity of a piezoinjector of a fuel injection system, which comprises a nozzle needle displaceable by a piezoactuator. Based on the instantaneous injection quantity, a selection is made among various control methods. In a ballistic injector mode, a first control method is carried out, wherein both a needle closing point in time is equalized and a needle travel time is also equalized. In a full stroke injector mode, a second control method is carried out, wherein a needle closing point in time is equalized, but the needle travel time is not equalized.