The present invention relates to a heart valve prosthesis having an annular body with a pair of flanges, and a closing element in the form of two or three flaps mounted through bearings into the body's recesses with freedom to be rotated. The annular body has a constant height on a greater portion of a ring circle, and a number of ledges equal to that of the flaps. The ledges are provided with flap rotation limiters. The flaps have ascending and descending surfaces oriented to the direct and reverse flow of blood, a side edge and an edge for joining the other flap. The descending surface of a flap is flat and the ascending surface thereof is spherically concave. The flaps have the minimal thickness on an axis of symmetry at the joining edge. The axes of rotation of the three flap embodiment are arranged relative to each other at an angle of 60° thereby to form the sides of an equilateral triangle. For the valve with two flaps the flange facing the direct flow of blood is thickened. Recesses for bearings enter into the thickened flange with the recesses having a lateral cylindrical surface and a concave bottom.