Thirty‐nine severely calcified aortic valves surgically removed were studied for amyloid deposits using the alkaline Congo red stain. Amyloid deposits were found in all the valves, in such quantities that they could be demonstrated using screening magnification (X 40). A close topographic relationship was found between amyloid and calcium deposits. In addition, histological evidence was found of prolonged fibroblast proliferation. In the light of more recent studies, which identify Congophilic cytofilaments in fibroblasts, as well as demonstrating fibroblast degeneration and decomposition in senile aortic valves, the following pathogenesis is suggested for “calcific aortic stenosis”; Mechanical injury of malformed aortic valves leading to fibroblast proliferation; fibroblast degeneration and decomposition with extracellular accumulation of cellular degradation products (among others Congophilic cytofilaments); calcium deposits in the cellular degradation products resulting in “calcific aortic st