This article presents a patient with portal hypertension in whom an unusual localization for portosystemic collaterals have incidentally been found. Upper abdominal sonography revealed tubular structures filling the whole perirenal and partially the perihepatic area, and their venous nature was demonstrated with duplex Doppler sonography. Spiral CT angiography identified the right-sided retroperitoneal location and mesenteric-lumbar route of the collaterals. Upper gastrointestinal endoscopy with antral biopsy and percutaneous liver biopsy were performed. Laboratory results and specimen evaluation revealed chronic active hepatitis due to hepatitis-B infection. Attention is drawn to the abnormal location of these vessels, together with the noninvasive nature and competence of CT angiography in demonstrating vascular pathologies.