Hypertrophic pyloric stenosis (HPS) is the most common infantile surgical condition and the standard treatment is open pyloromyotomy. Recently, laparoscopic techniques have rapidly advanced, and the laparoscopic approach has become widely adopted by pediatric surgeons. The aim of this study was to compare the clinical outcomes between open and laparoscopic pyloromyotomy. We retrospectively evaluated outcomes of pyloromyotomy for HPS by the open (OP) and the laparoscopic (LP) method. The procedures were performed at the Samsung Medical Center between September 2001 and March 2009. We analyzed patient age, sex, birth weight, length of hospital stay, postoperative length of stay (LOS), operating time, time to feeding commencement, postoperative vomiting frequency, the time to full feeding without vomiting, and surgical complications. A total of 54 patients were included in the study. There were 26 OP and 28 LP patients. There was no statistically significant difference in age, sex, birth weight, operating time, postoperative emesis. In contrast, postoperative LOS in the LP group was statistically significantly shorter than that in the OP group (2.0 vs. 3.3 days, p=0.0003) and time to full feeding was significantly shorter following LP. (p=0.018) There were no wound complications. Laparoscopic pyloromyotomy significantly reduced postoperative LOS and time to full feeding compared to open pyloromyotomy.