Until wide use of ultrasound in diagnostic procedures took its part, the only relevant procedures to diagnose Infantile Hypertrophic Pyloric Stenosis (IHPS) were clinical examination and X-ray of gastroduodenal tract. Use of diagnostic ultrasound avoids harmful effects of X-rays on immature children's tissues. Reliability of the procedure is very high. In the period between July 1993 and January 1999 we diagnosed 12 cases of IHPS in our Hospital by ultrasound examinations. Eleven patients were males between five and eight weeks of age, and one female was six weeks old. In six of them the finding was confirmed by radiological examination (on surgeon's request), in one neither radiological examination not surgery was performed, and five were operated on the basis of only ultrasound finding. In eleven operated patients ultrasound finding is proven by surgery.