Thirty three members of the Korean Association of Pediatric Surgeons were surveyed to determine the clinical manifestations and current management of infantile hypertrophic pyloric stenosis (IHPS). The members completed a registration form and a questionnaire that indicated their treatment preferences for patients treated during 1996. The response rate was 84.8% and 23 institutions participated. Three hundred and sixty-three cases of IHPS were analysed. The male to female ratio was 5.15:1. The presenting symptoms were nonbilious vomiting in 363 cases(100%), palpable mass in the upper abdomen in 200 cases(55.1%) and visible peristaltic waves in 67 cases(18.5%). Fluid therapy was done in 161 cases(44.4%) for preoperative preparation. Twenty patients(5.5%) were premature. There were 27 low birth weight babies(7.7%). The onset of symptoms ranged from 1 to 14 weeks of age with a peak occurrence at 2 to 4 weeks of age. Two hundred and thirty-six cases(66.6%) presented within 4 weeks of age. There was one set of male twins and a family history of twins. The modes of feedings were: breast feeding; 69 cases(24.5%), formula feeding; 176 cases(62.4%) and mixed feeding; 37 cases(13.1%). The preferred diagnostic modalities were ultrasonography(US) 229 cases(63.1%), UGI series 27 cases(7.4%) and US and UGI series combined 86 cases(23.7%). Only 21 cases(5.8%) were operated on without imaging study, ie. with positive physical finding. Perforation of the mucosa during pyloromytomy occurred in 5 cases. All were treated successfully with primary closure. Persistent vomiting over 2 weeks after operation were reported in 5 cases. Three wound infections, one aspiration pneumonia and one postoperative bleeding were reported. There was no mortality in 363 cases.