The mitral valve (MV) is a complex structure consisting of six components such as annulus fibrosus, leaflets, chordae tendineae, papillary muscles, posterior left atrial wall and left ventricular wall. These six components should be considered functionally a unit, since derangement of any one can cause MV dysfunction. Rheumatic pathology results in four forms of MV pathology—commissural (30%), cuspal (15%), chordal (10%) and combined (45%). This chapter covers the pathophysiology of mitral stenosis, echocardiographic assessment in MS prior to percutaneous mitral valvotomy, subvalvular pathology, left atrium, assessment of lesions in other valves, transesophageal echocardiography in PMV, Doppler assessment of mitral valve, pressure half-time, pulmonary hypertension, periprocedural monitoring, Post-PMV assessment, left atrial function, exercise echocardiography, and predictive value of echocardiographic assessment of MV morphology before PMV.