A textile heart valve prosthesis is manufactured by forming fabric in such a way as to obtain a valve geometry close to that of the native valve. The forming process leads to optimal closing geometry and limited deformation of the fabric structure during manufacture. The hydrodynamic performance of a fabric heart valve prototype is measured and compared with other commercially available heart valve prosthesis types. In vitro performance of the prototype is evaluated using a pulse duplicator simulating the left side of the human circulatory system, with a 70 ml cardiac output at a constant heart rate of 70 beats/min under a mean diastolic pressure of 100 Hg mm.