The authors reviewed the clinical and laboratory data from cases of hypertrophic pyloric stenosis (HPS) diagnosed at their institution from 2006 to 2008. They assessed and compared presentation of patients with HPS over time at their institution. A total of 118 patients were included in this study. An "olive" was palpated in only 13.6% of cases. This is in contrast to older studies, where more than 50% of the patients were reported to have a palpable "olive" depending on when the study was conducted. In patients from this institution, hypochloremia was present in 23% and alkalosis in 14.4%, which are less frequent than the incidence of these abnormalities in older studies. There was a change in the additional "classical" symptoms, represented by the lower percentage of infants in whom an "olive" was palpated and the lower numbers of patients with severe electrolyte imbalances. The reason for this change appears to be the frequent use of ultrasound.