OBJECTIVE The aim of this study was to evaluate the advantages or disadvantages of laparoscopic pyloromyotomy compared with open transumbilical fold pyloromyotomy. METHODS Thirty consecutive laparoscopic extramucosal pyloromyotomies (LP) performed from 1994 to 1997 were compared with 30 consecutive open pyloromyotomies (OP) performed during the same period with regard to age at operation, body weight, thickness of hypertrophied pyloric muscle, operating time, time of return to full feeding, frequency of postoperative emesis, surgical complications, and degree of surgical stress reflected by interleukin-6 (IL-6). LP was performed according to conventional techniques, and OP was performed using a transumbilical fold approach. RESULTS The groups were matched for age at operation, preoperative clinical and physical status, laboratory data, and size of the hypertrophied pylorus assessed by ultrasonography. There was a learning curve with LP; the average operating time required for the first 10 cases was significantly longer than the time required for OP, but later cases took just as long as OP cases. Time taken to full feeding was significantly shorter in the LP group than the OP group (LP, 38 hours v OP, 64 hours). One case was converted from LP to OP because of mucosal perforation. The incidence of postoperative emesis was significantly higher in the OP group than in the LP group (OP, 25% v LP, 3%). The mean length of hospitalization was significantly shorter in LP (P < .01). The intraoperative peak values of IL-6 in LP were significantly lower than those in the OP group (P < .01). CONCLUSIONS The advantages of LP are improved cosmesis, decreased surgical stress with earlier postoperative recovery, and shorter hospitalization. Because LP uses reusable devices, and the mean period of hospitalization is shorter, average operating costs could be reduced, representing a net saving in total hospital charges.