Hepatic arterial occlusion (HAO) is frequently encountered in patients receiving hepatic arterial infusion chemotherapy (HAIC) via an implanted port-catheter system. Usually, HAO precludes continuation of HAIC, and treatment for liver metastases is changed to systemic chemotherapy. However, two cases were encountered in which, even though HAO was diagnosed by arteriography via the port, the hepatic artery was actually patent. These cases illustrate that arteriography via the port is insufficient to confirm HAO.