The invention relates to a reciprocating piston pump having a magnet drive and a first displacement chamber and a second displacement chamber, which are separated from each other by a piston, wherein both displacement chambers are connected to each other by a fluid-conducting channel. An overflow valve is arranged in the channel and allows a preferred flow from the first displacement chamber to the second displacement chamber, wherein an additional return valve is arranged either in a transition region between an inlet and the first displacement chamber or in a transition region between the second displacement chamber and an outlet, an armature of the magnet drive being firmly connected to the piston.