In five patients with hepatocellular carcinoma, CT arterial portography (CTAP) and CT hepatic arteriography (CTHA) were performed serially by using a newly developed detachable Y-shaped tube with two valves that could be attached to a conventional angiographic sheath. Two catheters could be inserted into the conventional angiographic sheath without blood backflow by using the Y-shaped tube. One catheter could be easily and safety placed on the common or proper hepatic artery, and the other on the superior mesenteric artery. This detachable Y-shaped tube with two valves could make it easy to perform serial CTAP and CTHA examinations.