Hiatal hernia is a very rare disease in the pediatric population. However information from our esophageal atresia postoperative follow-up program has hypotheses; "Hiatal hernia may more frequently occur in postoperative esophageal atresia patients (EA group) than in the general pediatric population (GP group)" and "The tension on the esophagus after esophageal anastomosis may be an important etiologic factor of hiatal hernia in EA group". To prove the first hypotheses, we compared the incidence of hiatal hernia in the GP group with the incidence in the EA group. The Incidence in the GP group was obtained from national statistic data from Statistics Korea and Health Insurance Review and Assessment Service of Korea. The incidence in the EA group was obtained from the medical record and the imaging studies of our esophageal atresia postoperative follow-up program. To prove the second hypothesis, the presumptive risk factors for the development of hiatal hernia in EA group, such as the type of esophageal atresia, degree of esophageal gap, the stage operation and the redo-operation with resection and re-anastomosis of esophagus were analyzed statistically. The total number of patients in the EA group was ninety-nine and there were 5 hiatus hernias. The incidence of EA group (5 %) is significantly higher than incidence of GP group (0.024 %). (p=0.0001) The statistical analysis of the presumptive risk factors for hiatal hernia development in EA group failed to show any evidence of correlation between postoperative esophageal tension and the hiatal hernia. This study shows that the postoperative patients with esophageal atresia have high occurrence of hiatal hernia and should be followed up carefully to detect hiatal hernia.