Background: We evaluated the imaging features of portal vein aneurysm occurring at the umbilical portion and the relation between portal vein aneurysm of the umbilical portion and portal vein anomaly. Methods: Retrograde analysis was performed in 18 patients with portal vein aneurysm of the umbilical portion of the portal vein. We analyzed the size, shape, and imaging findings of portal vein aneurysm. In addition, we evaluated associated portal vein anomalies, specifically, the branching pattern of the intrahepatic portal vein and the position of the umbilical portion of the left portal vein. Results: The diameter of the portal vein aneurysm ranged from 1.5 to 2.2 cm and the shape of the portal vein aneurysm was saccular (n 14) or fusiform (n 4). Imaging findings of the portal vein aneurysm of the umbilical portion were typical for its vascular nature. Portal vein anomalies were seen in eight of 18 patients (44%): the right anterior segmental portal vein (n 7) or the right anterior and posterior segmental portal veins (n 1) originating from the umbilical portion of the left portal vein and a rightward deviation of the umbilical portion of the left portal vein (n 4). Conclusion: Due to its vascular nature, noninvasive diagnostic modalities can enable the detection of portal vein aneurysm of the umbilical portion, and there is a close relation between portal vein aneurysm of the umbilical portion and portal vein anomaly.