During last 20 years from 1959 to 1978, 75 cases of the congenital pyloric stenosis were admitted to department of pediatrics of Yonsei University College of Medicine, and evaluated clinically. The results obtained are asfollows: 1.Vomiting is usually developed during 2 to 4 weeks of life(38 cases, 50%) and the ratio of male to female was 6.5:1. 2. The incidence among siblings were 37 cases in 1st born, 20 cases in 2nds and 9 cases in 3rds. 3. The duration from onset to admission showed a eak incidence between one to two weeks(41 cases among 75 cases) 4. In the symptoms and physical findings; Non-bile stained vomiting was developed in all of the cases, abdominal masses palpated in 67 cases(90%), and visible peristaltic waves were observed in 25 cases(33%). 5. Metabolic alkalosis was developed in 25 cases (33%), serum Na concentration was ranged between 130~150mEq/l in 59 cases and serum K concentration between 3~5mEq/l in 65 cases. 6. 70 cases received surgical treatment. 69 cases were improved, and one case was expired due to aspiration pneumonia. 4 cases were improved with medical treatment including anticholinergics.