Pyloric stenosis is a common infantile disorder typically occurring between 2 weeks and 8 weeks of age. Presentation outside this range and in premature infants is uncommon and often atypical. We present three cases, a pair of premature twins and a 5.5-month-old infant with pyloric stenosis. We highlight that despite their difference in size and weight, ultrasound examination remains a reliable diagnostic tool. However, pyloric measurements should be interpreted in combination with the other dynamic features on ultrasound.