A new catheter was developed for the cardio-renal assist during intra-aortic balloon counterpulsation. The catheter consists of both a large balloon of conventional IAB (TMP balloon) located at the distal end of the catheter and an additional small balloon 10 cm distant from the large balloon with common lumen and single shaft. Experimental study was carried out in the mock circulatory system simulating the descending aorta employing a conventional IAB catheter as a control. It was demonstrated that the flow in the mid portion between both balloons could be increased maximally by as much as 28% of that of the control under the continuous flow and 214% under the pulsatile flow. The double balloon catheter was considered to improve the renal perfusion as well as the coronary perfusion.