M-mode, two-dimensional and Doppler echocardiography enable evaluation of morphologic changes in valvular structures, detection of secondary changes in cardiac chambers and left ventricular function and quantification of blood flow patterns. In mitral stenosis, with M-mode echocardiography the diagnosis can be established on the basis of defined criteria, two-dimensional echocardiography enables planimetric calculation of the orifice area and Doppler echocardiography allows determination of the transvalvular pressure gradient and estimation of orifice area as well as detection of concomitant lesions. In mitral regurgitation, M-mode and two-dimensional echocardiography are less sensitive in its detection but they may be useful in delineating the etiology and whether the disease is of acute onset or chronic; the severity can only be judged indirectly on the basis of chamber dimensions. Doppler techniques render extremely sensitive and specific detection of mitral regurgitation as well as a means of quantifying severity. In this lesion, echocardiographic parameters have proven useful in the timing of valve replacement through early detection of myocardial dysfunction. In aortic regurgitation, M-mode and two-dimensional echocardiography may be useful in establishing the diagnosis, etiology, duration and, through assessment of dimensions and motion, estimating the severity as well. Doppler echocardiography is extremely sensitive and specific in the detection of aortic regurgitation and, additionally, provides a quantitative means for evaluation of severity. In aortic stenosis, both M-mode and two-dimensional echocardiography are sensitive in detection of changes in valve structure and motion but these methods are not capable of rendering reliable quantification of severity. Doppler techniques readily identify aortic stenosis and render, in addition, a close estimation of the transvalvular pressure gradient.