A clinical observation was performed on 19 cases of congenital hypertrophic pyloric stenosis, admitted to the pediatric department of preshyterian medical cneter during the past 4 years and 7 months from January 1973 through July 1977, and the following results were obtained. 1. The incidence of congenital hypertrophic pyloric stenosis amont the total admitted patients was 0.34% with the increment of the patient in recent 2-3 years. 7 patients (36.7%) were first born baby and the male to female ratio was 5.3:1. The high incidence revealed in breast fed infant (63.1%). 2. The average age on admission was 40 days with little weight gaining on admission compared to the birth weight. 3. In the majority of the cases(80%), the disease onset started within 3 weeks of age. Projectile vomiting and dehydration were observed in all cases, and the epiagstric mass was palpated in only 4 cases (21.2%)/ 4. In 15 cases (79%) and 12 cases (62.9%), the hypochloremia and alkalosis were developed respectively. 5. Plane abdominal X-ray showed one bubble air shadow in 11 cases (57.8%) and the string sign was seen in 16 cases (84.2%) on barium meal study. Fredet-Ramstedt operation was performed for 15 cases immediately after the diagnosis. One case expired.