Abstract: A fuel injection pump for internal combustion engines having a pump piston driven to reciprocate by a cam drive, guided axially in a cylinder bore of a cylinder bush in which with one face end the pump piston defines a pump work chamber. The control piston has on a jacket face an oblique control edge that cooperates with a control opening in the cylinder bore. This control opening is embodied in an oval shape for the sake of a slight prepumping effect at the injection onset and a rapid opening at the end of injection, and is disposed obliquely enough in the cylinder liner so that a longitudinal axis of the oval extends approximately parallel to the oblique control edge.