The aim of this chapter is to focus on the three-dimensional echocardiography in PMV. Henry in 1975 for the first time planimetered the mitral valve orifice, a measurement hitherto not available without cardiac catheterization. The difficulties in clearly imaging the smallest mitral valve orifice in a diseased valve were partly overcome with the advent of Doppler echocardiography using methods like the continuity equation and the pressure half time. The ability to accurately localize the smallest orifice has essentially made three-dimensional (3D) echocardiography the Gold standard for the assessment of rheumatic mitral stenosis. Though invasive, 3D transesophageal echo (TEE) done simultaneously during preprocedural evaluation to rule out left atrial thrombi, gives the best pictures to study the mitral valve. The mitral valve apparatus is a complex three-dimensional structure consisting of the leaflets, the mitral annulus, the chordae tendineae, the papillary muscles and the left ventricle itself. Three-dimensional echocardiography in rheumatic mitral stenosis, mitral valve anatomy, procedural 3D TEE in the interventional catheterization laboratory, left atrial appendage, and imaging protocol are covered in this chapter.