The invention relates to a biological or artificial valve prosthesis (4, 5) for use in the human or animal body for replacement of an organ valve or a vessel valve, in particular a cardiac valve prosthesis or venous valve prosthesis, with a stent (8) or without a stent, with a supporting valve framework, with at least one valve (7) and with at least one conductor loop (2) that forms the inductance of an electrical resonance circuit. In order to provide a simple and inexpensive valve prosthesis that can be viewed in the MR imaging technique and is also easy to implant, the invention proposes that the at least one conductor loop (2) forms the valve framework and/or the valve (7) or supporting areas of the valve framework and/or supporting areas of the valve (7).