PURPOSE: Hypertrophic pyloric stenosis (HPS) is a common condition affecting infants that causes severe projectile non-bilious vomiting in the first few months of life. Although open pyloromyotomy is the standard treatment for HPS, recently, the laparoscopic approach has rapidly been adopted by pediatric surgeons. The aim of this study is to determine the efficacy and safety of laparoscopic pyloromyotomy by comparing the clinical results of laparoscopic and open pyloromyotomy. METHODS: Between January 2007 and September 2012, a cohort of 69 children who underwent pyloromyotomy at Seoul National University Children's Hospital were followed; open pyloromyotomy (OP, n=56) and laparoscopic pyloromyotomy (LP, n=13). A retrospective analysis of patient's characteristics and clinical outcomes in patients with open or laparoscopic pyloromyotomy for HPS was performed. The evaluated characteristics included gestational age, sex, birth weight, age and weight at operation. Clinical outcomes included operation time, length of hospital stay, time to postoperative full feeds without vomiting, number of postoperative vomiting and complications. RESULTS: There were no significant differences in characteristics, length of hospital stay and time to postoperative full feeds without vomiting between the two groups. Incidence of postoperative vomiting in the LP group was significantly lower than that in the OP group (OP: 5.07+/-4.60 vs. LP: 2.00+/-2.16, p=0.035). In contrast, the operation time was longer, following the LP group (OP: 26.30+/-9.95 vs. LP: 44.15+/-19.56, p<0.001). Complications such as perforation of mucosal layer (OP: 2 vs. LP 1, p>0.999) and wound problems (OP: 4 vs. LP 1, p>0.999) were found to be similar in both groups. CONCLUSION: Both open and laparoscopic pyloromyotomy are safe procedures for the management of hypertrophic pyloric stenosis. Incidence of vomiting was statistically superior in the laparoscopic group. In addition, postoperative complications were fewer in this group. However, an improvement in the operation time will be needed for the future development of laparoscopic pyloromyotomy.