During the years gear pumps have become a very common tool in thermoplast extrusion. In opposition to this, gear pumps are quite unknown for extrusion of rubber profiles. Starting with design and working principle of a gear pump the combination of extruder and gear pump is described from a processing and controlling point of view. The resulting advantages concerning output accuracy, overcoming of high tool resistances, application for degassing extrusion, energy saving and extension of the field of application of production lines, are explained.