A device for influencing cell-growth mechanisms in vessels, in particular blood vessels, of a human or animal body, wherein to influence the cell growth mechanisms there is provided an excitation device (5; 5") which is adapted to produce stimulation currents in a region to be treated of the vessel (3; 3"), wherein the frequency and/or the modulation frequency of the stimulation currents is in the range of frequencies at which distribution of secondary messenger substances controlling cell growth in the cells of the vessel (3; 3") is influenced. Implant for influencing cell-growth mechanisms in such vessels.