For the past several years we have studied the possible clinical usefulness of recording the low-frequency precordial vibrations put in motion by the cardiac cycle. We have confined our analysis to the technique of apex cardiography. Our approach has been that of clinical empiricism; specifically, we have prestated the clinical variable, using standard disease patterns, and then analyzed the apex cardiographic response to this variable. Subsequently, we altered pharmacologic and physical variables and again noted the apex cardiographic response. Simultaneously, and in some instances earlier, other investigators have also studied precordial vibrations using the same or different methods. The consensus seems to indicate that there is clinically useful information to be gained by analysis of this low-frequency spectrum. It is important to appreciate this fact, inasmuch as the diversity of instruments, nomenclature, and method may alarm and dissuade others from gaining experience in this field.