Echo Doppler makes a fundamental contribution to the non-invasive quantification of mitral valve disease. It enables calculation of gradients and of orifice surface area in mitral stenosis. The quantification of mitral insufficiency is also possible though more difficult: it is based upon the combination of semi-quantitative and quantitative methods, in particular the calculation of regurgitation fraction obtained by comparison of flow rates at different orifices in cases of pure regurgitation. Finally, the calculation of pulmonary artery pressures from a Doppler record in tricuspid and pulmonary insufficiency can be used to assess the effects of mitral valve disease on the pulmonary circulation. Echo Doppler thus provides a reliable non-invasive hemodynamic assessment of mitral valve disease and should lead to a reduction in the number of invasive investigations in this type of valve disease.