Abstract: A heart valve prosthesis disclosed in two- and three-leaflet versions includes a ring-shaped body, leaflets, and leaflet turn stops. For the two-leaflet version, the stops represent two pairs of prominences located on a body end surface facing the blood down-flow. The first pair has internal surfaces, at least partially made flat, adapted to interact with flat sections of the leaflets to restrict the return blood flow in the closed position. The first pair is equipped with at least two rests interacting with a leaflet top surface facing the blood down-flow in its open position determining a leaflet turning angle. Each prominence of the second pair is located opposite a portion of the lateral surface of the corresponding leaflet most distant from a leaflet central surface and can interact with its internal surface with that part of the lateral surface during opening of the heart valve prosthesis.