Mechanical prosthetic valve regurgitation may be either periprosthetic or intraprosthetic. The later is usually mild, occurring in the majority of normally functioning valves and is due to the 'regurgitant flow' closing the valve. An unusual case is reported of intermitent intraprosthetic regurgitation through a normally functioning aortic Medtronic-Hall prosthesis caused by tissue ingrowth below the valve 4 years after implantation