WHEN I WAS a second-year medical student in the 1960s, one of the first patients I was shown was a man with severe aortic stenosis secondary to rheumatic heart disease. I still remember this patient's face and the distinctive, rough, systolic ejection murmur that filled systole, obliterating the second heart sound. Since then, rheumatic cases of aortic stenosis have become rare, but severe aortic stenosis is still one of the commonest causes of valvular heart disease seen in hospitalized patients. In the more than 30 years since I saw my first patient with aortic stenosis, much has been learned concerning the pathophysiology of this condition. Indeed, there are studies currently under way seeking to alter the pathological sequence in this disease that eventually leads to aortic valve replacement.