One- and two-dimensional echocardiography are the most reliable methods of detecting mitral stenosis. Planimetry of the mitral valve area allows a reliable assessment of the degree of stenosis in 75% of all patients. Doppler echocardiography offers the possibility of measuring the transmitral pressure gradient and to determine pressure half-time, from which the mitral valve area can be calculated. The transmitral pressure gradient, however, undergoes considerable day-to-day variations and therefore its value for quantification is limited. The pressure half-time and planimetry of the mitral valve area are supplementary methods, for they allow the determination of the functional and the anatomic mitral valve area. These combined techniques allow a reliable quantification of the degree of mitral stenosis in about 90% of all patients. Doppler and color-coded Doppler echocardiography are sensitive tools in detecting accompanying disorders as mitral and aortic regurgitation or aortic stenosis. Subsequent disorders of mitral stenosis such as pulmonary hypertension or relative tricuspid incompetence can be assessed. In selected cases mitral valve surgery may be performed without prior catheterization.