Hypertrophic pyloric stenosis of infant is relatively common disease, the roentgenologic examination gives unequivocal and reliable information than other diagnostic procedures in diagnosing this disease. Total 19 cases of hypertrophic pyloric stenosis, admitted at Dong-San presbyterian hospital during 1969 to 1977, studied by means of roentgenologic findings. 16 of 19 had roentgenological examination. The results are as follows. 1. 84.2% are male. 2. Between 1 month to 6 months of age are 11 cases, about 58%. 3. Roentgenologic findings are; String sign 11 (68.7%), Beaked sign 10 (62.5%), Tit 5, Shoulder 5 (each 31.3%) and Mushroom 2 (12.5%), Delayed emptying were 7 cases (43.8%).