BACKGROUND: Infantile hypertrophic pyloric stenosis is the common disease of neonate and infant but its etiology and pathogenesis are still obscure. Frequent vomiting lead to electrolyte imbalance in infantile hypertrophic pyloric stenosis. METHODS: This study is a clinical analysis of the 30 cases of infantile hypertrophic pyloric stenosis (IHPS), that was surgically treated at the Department of Surgery, St. Columban Hospital during period of 8 years from January, 1990 to December, 1997. RESULTS: 1) The ratio of male to female was 3.3:1 and 50% of patients was first-born baby. 2) The most prevalent age group was between 3 to 4 weeks (20%). 3) The body weight percentile at admission was lower than 3 percentile in 14cases (46.7%). 4) Nonbilous projectile vomiting was noted in all cases. 5) In 15 cases (50%) of patients, the onset of symptoms was at 1 to 2 weeks of age. 6) The duration of symptoms was highest between a week to 3 weeks (50%). 7) The most frequent physical finding was palpable abdominal mass (60%). 8) At admission, clinical jaundice was noted in 3 cases (10%). 9) Hypochloremia was noted in 15 cases (50%) and hypokalemia in 6 cases (20%). 10) All cases were treated with Fredet-Ramstedt pyloromyotomy and duodenal perforation was complicated in 1 case. 11) Electrolyte abnormalities at admission did not significantly influence on the hospital stay. CONCLUSIONS: Through the surgical treatment so called Fredet-Ramstedt pyloromyotomy after accurate and rapid correction of dehydration and electrolyte imbalance, it can be cured.