We describe our experience performing cardiac catheterization of the left coronary artery in a patient with an aneurysm of the ascending aorta using a double-catheter technique. A 7 Fr guiding catheter was advanced into the aortic root and a longer multipurpose diagnostic catheter was passed through the guiding catheter, which enabled the extension of the whole catheter system. In addition, this technique allowed us to reach the ostium of the left coronary artery and perform coronary angiography.