Late-onset primary gastric outlet obstruction in childhood is a rare condition. Only 8 cases of such were reported. Diagnosis should be considered while ruling out mechanical and structural lesions. Up to now, Heineke-Mikulicz pyloroplasty has been the standard treatment. However, we succeeded in treating this condition by using pneumatic dilation. There is no sign of recurrence for 1 year. We propose the etiology, diagnosis, and the relationship between late-onset primary gastric outlet obstruction and esophageal achalasia in childhood.