We evaluated intracorporeal pyloromyotomy (ICP) as an alternative to extracorporeal pyloromyotomy (ECP) in infants with hypertrophic pyloric stenosis. From July 1994 to June 2002, 75 patients underwent ICP, and 29 patients underwent ECP through supraumbilical incisions. The medical charts were reviewed retrospectively with regard to operating time, time to return to full feeding, complications, and outcome. The average operating time in the ICP group was significantly longer than in the ECP group (56.4+/-13.6 vs. 48.7+/-16.3 min; p=.004). However, the average time to return to full feeding in the ICP group was significantly shorter than in the ECP group (2.1+/-1.6 vs. 2.9+/-1.9 days; p=.002). Extension of the skin and/or fascial incision was necessary in two of 75 patients in the ICP group, compared with 11 of 29 patients in the ECP group ( p<.0001). There were four (5.3%) wound infections and one (1.3%) mucosal perforation in the ICP group, compared with two (6.9%) wound infections in the ECP group. ICP allows patients to return to full feeding earlier than ECP does, resulting in a shorter hospital stay. ICP through a supraumbilical incision is superior to the ECP technique.