Infantile hypertrophic pyloric stenosis can be corrected by either open (OP) or laparoscopic pyloromyotomy (LP). LP may provide clinical benefits of reduced time to postoperative full feeds and reduced postoperative inpatient stay, but the cost effectiveness is not known. Our aim was to compare the cost effectiveness of laparoscopic and open pyloromyotomy.OP and LP were compared in a multicenter randomized double-blind controlled trial, for which the primary outcomes were time to full feeds and time to discharge. In order to undertake a detailed cost analysis, we assigned costs, calculated on an individual patient basis, to laboratory costs, imaging, medical staff, medication, ward, operative, and outpatient appointments for 74 patients recruited from one of the participating centers. Data (mean ± SEM) were compared using linear regression analysis, adjusting for the minimization criteria used in the trial.Operation costs were similar between the two groups ($3,276 ± $244 LP versus $3,535 ± $152 OP). A shorter time to full feeds and shorter hospital stay in LP versus OP patients resulted in a highly significant difference in ward costs ($2,650 ± $126 LP versus $3,398 ± $126 OP; P = .001) and a small difference in other costs. Overall, LP patients were $1,263 (95% confidence interval $395-$2,130; P = .005) less expensive to treat than OP patients. Sensitivity analyses of laparoscopic hardware usage and of incomplete pyloromyotomy indicated that LP was consistently less expensive than OP.LP is a cost-effective alternative to OP as it delivers improved clinical outcome at a lower price.