Mechanical performance of the heart depends on the physiologic interplay of its systolic and diastolic function. However, the cardiologist is used to defining left ventricular (LV) function only in terms of ejection fraction, cardiac output and blood pressure, thus observing only systolic function. In the last 10 to 15 years experience has revealed that, despite the presence of a normal LV systolic function, alterations of LV diastolic function may impair exercise tolerance and may be responsible for the clinical picture of about 30% of patients with a definite diagnosis of congestive heart failure. Doppler echocardiography has emerged as the most feasible and accurate noninvasive technique in assessing LV diastolic function in the clinical setting. Combined Doppler evaluation of transmitral and pulmonary venous flow velocity recordings, by transthoracic approach, allows us to obtain clinically relevant information on LV relaxation, LV filling, LV compliance, and LV end-diastolic and mean filling pressure, as well as on left atrial function, in more than 95% of patients referred to the echo-lab. With this combined evaluation different types of filling patterns have been identified. Clinical evaluation, together with structural/functional information obtained by M-mode and two-dimensional echocardiography, and mainly with detailed analysis of these LV filling patterns by Doppler, allow for a fairly accurate identification of various diastolic abnormalities, as well as the presence of diastolic dysfunction, i.e., increased filling pressures. Diastolic failure, characterized by the association of diastolic dysfunction and symptoms of pulmonary venous congestion, can now be more precisely identified following the criteria established by the Working Group on Diastolic Heart Failure of the European Society of Cardiology. Echo-Doppler age-adjusted normal values of indices of impaired LV relaxation and filling, along with cut-off values of Doppler signs of reduced compliance or increased filling pressures have been defined by the Working Group, and are herewith reported for practical purposes. Furthermore, as a reference for an advanced echo-lab, a "decalogue" of diastological performances is suggested.