Abstract: In a method and a device for filling needle-free injectors, it is proposed that filling takes place through the injector discharge opening and where the piston stopper has been previously inserted. Filling takes place in such a way that, independently of tolerances of the injector, the interior space is filled to the brim in an at least approximately bubble-free manner. It is not absolutely necessary to measure or dose the liquid to be filled. The filled state is either established through the disappearance of the vacuum in the interior space, or through the piston having reached a specific position during displacement.