Enteric cysts are very rare lesions among mediastinal cysts and are seen in infants with other congenital lesions. Two male babies who had right posterior mediastinal cystic lesions were admitted. Cystic lesions were excised. Cylothorax (200 cc/day) in one patient who had congenital vertebral anomalies was encountered. Ligation of ductus thoracicus was made by mass ligation procedure. Associated congenital lesions and surgical complications of enteric cysts are discussed with the review of the literature.