A prosthetic venous valve having a two-piece housing which includes upstream and downstream sections. The upstream section contains a circular seat against which an occluder comes in sealing contact when the valve is in its closed position. The downstream housing section is shaped so as to prevent escape of the occluder downstream and to halt the reciprocating motion of the occluder in the open position where there is an open pathway past the occluder. A plurality of fins on the interior of the downstream housing section or on the surface of the occluder assure there is a blood flow path downstream past the occluder in the open position. The two-piece construction allows the housing sections to be axially spaced apart so that blood comes in contact with the interior surface of the patient's vein immediately downstream of the upstream section of the housing. Such arrangement is biologically advantageous and permits momentary deflections of either of the housing sections from its normal coaxial orientation without harm to the valve or disruption of its functioning.
