Transesophageal echocardiography (TEE) is a useful tool for assessment of cardiac function in patients undergoing cardiac surgery or in patients undergoing non-cardiac surgery who have cardiovascular complications. Left ventricular (LV) function is composed of systolic function, diastolic function, preload and afterload. To assess systolic and diastolic function several methods are used, and we must use them based on the property of each parameter. Both systolic and diastolic functions are load dependent. To assess the systolic function, ejection fraction (EF) is commonly used. Transmitral flow (TMF) and pulmonary vein flow patterns are commonly used to assess the diastolic function. Newer techniques including mitral annular velocity and color M-mode TMF propagation velocity (Vp) may be less sensitive to changes in loading conditions. LV dP/dt is not affected by preload, and myocardial performance index (Tei index) can be used to assess both systolic and diastolic functions. Tei index is also useful to assess right ventricular function. The recently developed real time 3-dimensional system provides accurate and objective information, such as LV volumetry, wall motion, dyssyncrony and valvular pathology.