A total of 28 068 infants were studied to investigate whether universal ultrasound screening for developmental dysplasia of the hip results in fewer delayed presentations than selective screening, and whether the screening protocol affects subsequent treatment. The rate of delayed presentation was not lower with selective screening compared with universal screening but all cases of delayed presentation in this cohort were administrative errors. There were no sonographic errors (false-negatives). The treatment rate was significantly higher with universal screening but infants were treated earlier and were significantly less likely to require any surgical intervention. Those requiring surgery were less likely to require open reduction or pelvic osteotomy.