Congenital internal carotid artery (ICA) agenesis is a rare abnormality. People with this abnormality usually have adequate collateral circulation and remain asymptomatic for many years. However, patients may also present with pulsatile tinnitus, headache or blurred vision, or rarely with ischemic stroke or subarachnoid hemorrhage. Diagnosis is usually incidental with the performance of carotid artery Doppler ultrasonography or cervical/cranial magnetic resonance imaging owing to other symptoms. ICA agenesis might also be misdiagnosed as ICA occlusion. In this manuscript, we report a patient with ICA agenesis who initially presented with facial paresthesis and was referred to our center for interventional therapy for left-sided ICA occlusion.