Fine strands associated with prosthetic heart valves have been demonstrated with transesophageal echocardiography, but the pathologic identity of these strands is unclear. A case of a man with a prosthetic aortic Medtronic-Hall valve with prominent valve strands and recurrent strokes is discussed. The patient underwent valve replacement surgery, and histopathologic examination of the strands identified them as Lambl's excrescences.