It has been definitely established that theophylline with ethylenediamine has a favorable influence on the dyspnea of cardiac failure.1These results have been attributed in part to the effect on the coronary and cerebral circulation. The present investigation was undertaken in the hope that further information might be obtained relative to the action of the drug in cardiac failure. We are concerned with the effect of the intravenous administration on the intrathecal and venous pressures and on bronchial obstruction. In the study of the intrathecal pressures the patient was placed on the side in a horizontal position with the head supported by two pillows. The puncture was made in the lumbar region and the pressure recorded by a water manometer. Pressure applied to the cervical veins before and after each study always produced a temporary increase in pressure. The venous pressure was measured by a modification of the method