The advantages of an early diagnosis of developmental dysplasia of the hip are well established. Early diagnosis means a shorter, less invasive course of treatment with more favorable results and fewer complications. In the Netherlands, the number of neonatally diagnosed cases is very low. Early detection of developmental dysplasia of the hip has become a regular part of the program for child health surveillance. This paper documents the results of a prospective cohort study designed to determine the validity of a standardized screening protocol for early detection of developmental dysplasia of the hip in infants during their first 6 months.