Echocardiography is an accepted diagnostic procedure in clinical and investigative cardiology. The expanded application of the noninvasive technic is in a phase of development, and problems in instrumentation and interpretation still persist. Proper examination of the heart by reflected ultrasound requires a skilled, well trained operator with a thorough knowledge of cardiovascular anatomy and physiology. To best accomplish the visualization of intracardiac structures, a strip-chart recorder is essential. The anatomy and motion of the mitral, tricuspid, aortic and pulmonary valves can be evaluated by this technic. Mitral stenosis, idiopathic hypertrophic subaortic stenosis, atrial myxoma and pericardial effusion are disorders that can be accurately diagnosed by echocardiography. If used in conjunction with the clinical, electrocardiographic and roentgenologic findings, echocardiography is useful in the evaluation of numerous cardiac disorders. Its use in the field of congenital heart disease has exceeded initial expectations. When combined with phonocardiography and cardiac catheterization, echocardiography has extended our knowledge of the genesis of heart sounds, murmurs and left ventricular function. In addition, the technic is useful in measuring the internal dimensions of the ventricles, atria and outflow vessels. These measurements can be used with reasonable accuracy to estimate ventricular volumes and ejection fractions in normal subjects. However in patients with grossly dilated ventricles or in those exhibiting localized contraction abnormalities, the correlation with ventriculography is unreliable. Newer technics, such as compound-B ultrasonography, which produces a two-dimensional cross-sectional image of intracardiac structures, and multiscan echocardiography, may provide a more accurate anatomic display of cardiac chambers and outflow vessels.