ALTHOUGH the vectorcardiogram has been studied extensively during the past 15 years, its clinical value is still unsettled. This is due in part to the fact that fundamental problems regarding the physical properties of the heart's electric field remain unsolved. The lack of precise knowledge concerning the electric field of the heart raises difficulties in deciding upon proper electrode placement and recording techniques. Arguments based on physical concepts which condemn a particular lead system as unsound may also be applied to any of the electrocardiographic leads. Nevertheless, no one could reasonably deny the clinical value of the electrocardiogram. This is true even though electrocardiography has been regarded by many as an empiric science. Through the correlation of many thousands of records with clinical and autopsy data, the diagnostic and prognostic reliability of the electrocardiogram has become established. The vectorcardiogram must also be put to this test to determine its