The pathophysiologic processes underlying valvular stenosis at the aortic and mitral positions are quite different. Mitral stenosis is an outcome of rheumatic fever. Rheumatic fever is quite unusual in this country but it and its sequelae, rheumatic valvular disease, persist as major public health problems in the Third World. Aortic stenosis is most commonly the result of calcific degeneration of a normal tricuspid aortic valve in the elderly or the result of rheumatic fever but can also develop in a congenital bicuspid aortic valve which becomes progressively more stenotic with age and the wear of abnormal flow patterns.