Achalasia is a functional disorder of a short segment of the lower esophagus showing obstruction of the esophagogastric junction. Dysphagia. regurgitation and weight loss are outstanding features,however, complicated pulmonary troubles aspiration pneumonitis, bronchiectasis, lung abscess etc. --are sometimes more apparent than the disease entity in children though achalasia is rarely encountered in children. During the period of January, 1961, to May, 1968, the authors experienced 9 cases of achalasia of the esophagus in Chest Surgery Department,N.M.C. 1. Seven of nine were male and four were under 5 years of age. 2. So-called symptoms triad noted in almost every case, and 3 of 4 children showed recurrent attacks of pneumonitis. 3. Chest film showed widened superior mediastinum by dilated esophagus in 6 cases, and pulmonary infiltrations in 3 cases of children. 4. Preoperative diagnosis were achalasia,esophageal stricture by rodent-cidal ingestion and suggestive esophageal cancer in 7 cases,one case and remaining one case. respectively. 5. Modified Heller procedure was performed in all cases with definite diagnosis of achalasia at operation table in misdiagnosed 2 cases. 6. Immediate postoperative complications were 2 cases of wound infection and one case of atelectasis and no operative mortality encountered. 7. Seven of nine showed excellent result of operation, and good in one case. Remaining one case failed relieving obstruction and underwent interposition of ileocolonic segment with excellent result.[KTCS 1968;1:53-60]