The mitral valve annulus is a complex structure that is an integral part of the mitral valve apparatus. The annulus plays an active role in mitral valve leaflet coaptation and in left atrial and ventricular function. The annulus is susceptible to disease processes that are distinct from those that affect the mitral valve leaflets. Advanced annular calcification may extend onto the mitral valve leaflets, thereby causing increased diastolic gradients across the mitral valve. This review highlights risk factors for mitral annular calcification, features of calcific mitral stenosis, differentiation from rheumatic mitral valve disease, and the echocardiographic approach to this disorder.