Methods are now available for determining left ventricular chamber dimensions, volume, volume curves, wall thickness and mass. These observations, when taken together with left ventricular pressure, can be used to characterize the left ventricle as a pump and determine end-diastolic volume, stroke volume, ejection fraction, rates of ejection and filling, mass, work and work components and power. Methods for deriving these values and their significance in the evaluation of the functional state of the left ventricle in patients with heart disease are discussed. © 1969.