BACKGROUND We conducted a prospective, randomized trial comparing protocol to ad libitum (ad lib) feeding after laparoscopic pyloromyotomy. METHODS Infants undergoing laparoscopic pyloromyotomy were randomized to protocol versus ad lib feeding strategies. The protocol started with Pedialyte® two hours post-operative. This was repeated by another round of Pedialyte®, then two rounds of half-strength formula or breast milk, followed by two rounds of full strength formula or breast milk, followed by the home feeding regimen, at which time the patient was discharged if feeding well. The ad lib group was allowed formula or breast milk two hours after the operation and considered for discharge after tolerating three consecutive feeds. The primary outcome variable was the length of postoperative hospitalization. RESULTS One hundred fifty infants were enrolled between January 2010 and December 2011. There were no differences in patient characteristics at presentation. While the ad lib group reached goal feeds sooner than the protocol group, this did not translate into a difference in duration of postoperative hospitalization. There were more patients with emesis in the ad lib group after goal feeding was reached, but no difference in readmissions. CONCLUSIONS Ad lib feeding allows patients to reach goal feeds more rapidly than protocol feeding following laparoscopic pyloromyotomy. However, this goal is usually reached beyond discharge hours, resulting in a similar duration of hospitalization.