The effect of digitalis on the coronary vessels or on the volume of coronary flow has received a very moderate amount of attention. The clinical and experimental evidence for or against any change in coronary flow with the administration of digitalis has been conflicting and not altogether convincing. Clinical observation of the effect of digitalis cannot be adequately controlled, and there is always the possibility that a favorable or untoward result following the administration of digitalis might equally have ensued if the drug had not been given. When the effect of digitalis on auricular fibrillation, on minute volume output or on edema is considered, one has measurable results to record. This is not possible in the case of the effect of digitalis on coronary flow. Our own clinical experience led us to believe that untoward effects might occur with the use of digitalis in coronary disease, and that these effects