OBJECTIVE Atropine sulfate (atropine) and pyloromyotomy were compared for managing infantile hypertrophic pyloric stenosis (IHPS). METHODS From 1996 to 1998, cases of IHPS treated surgically (pyloromyotomy; n = 20) or medically (atropine; n = 14) at separate institutions were compared retrospectively with regard to status on presentation, physical symptoms and signs, progress, and costs. Atropine was given orally, then intravenously if ineffective. Refractory cases were referred for pyloromyotomy. RESULTS All subjects were matched for clinical and physiological status on admission. Oral atropine alone was effective in 11 cases, was converted to intravenous atropine in 2 cases, and was terminated in 1 case because of hematemesis. Two cases were referred for pyloromyotomy. All pyloromyotomies were successful. Atropine took on average, 2.6 days to take effect. The difference in time taken for normalization of pyloric muscle thickness between the 2 groups was not significant. Average time to return to full feeding was longer in the atropine group (P<.01). Costs were lower in the atropine group (P<.01). There were 2 wound infections in the pyloromyotomy group, but no adverse effects of atropine. There were no recurrences in either group. CONCLUSIONS This study provides reasonable evidence to support a trial of atropine in IHPS.