A case of azygos and paraesophageal varices presenting as a posterior mediastinal mass in a 15-month-old infant with biliary atresia is described. The patient was evaluated for living donor liver transplantation because of repeated cholangitis after Kasai operation, and plain CT scan demonstrated a mass in posterior mediastinum. The operation of mediastinal tumor resection was planned before liver transplantation in order to exclude malignant disease, however, possibility of paraesophageal varices remained. Contrast-enhanced magnetic resonance imaging clearly demonstrated azygos and paraesophageal varices in posterior mediastinum. Living donor liver transplantation was performed successfully without ligation of paraesophagogastric varices. Contrast-enhanced CT demonstrated distinctly decreased mediastinal mass one month after transplantation.