We retrospectively reviewed 223 infants who underwent pyloromyotomy for hypertrophic pyloric stenosis (HPS) at our institution from January 1984 to May 1990. Each patient's postoperative feeding regimen was determined by the attending surgeon. The four distinct regimens used were as follows: A (n = 66): NPO overnight (> 10 h) with cautious feeding advancement every 4 hours x 2, then every 2 hours x 2, then every 1 1/2 hours x 8, then ad lib; B (n = 46): NPO until 6 to 8 hours postoperatively with the same cautious feeding advancement as in A; C (n = 42): NPO until 6 hours postoperatively with accelerated feeding advancement every 2 hours x 8, then ad lib; D (n = 69): NPO until 6 hours postoperatively with accelerated feeding advancement every 1 hour x 12, then ad lib. There were no significant differences in age at diagnosis or degree of dehydration among groups. From group A to group D, there was a progressive increase in amount and incidence of postoperative vomiting, both after the first three feedings and in the total postoperative period. However, patients in groups C and D had a shorter postoperative hospital stay and lower charges than did patients in groups A and B. Following discharge, no patient was readmitted for vomiting or dehydration. We conclude that feedings started 6 hours after pyloromyotomy for HPS with accelerated feeding advancement every 2 hours increases the incidence and frequency of postoperative vomiting, but not unacceptably, and results in a significantly shorter postoperative stay.