In 1969 universal clinical screening for neonatal hip instability was formally adopted in the United Kingdom with the aim of detecting and treating children considered to be at high risk of congenital dislocation of the hip (CDH). However, clinical screening is associated with both false positive and false negative diagnoses and has never been evaluated in a randomised trial. The emergence of hip ultrasound provides renewed impetus to reconsider and formally evaluate screening for CDH. Ultrasound imaging of the newborn hip may be used as a screening test and to assess and manage infants with clinically detected hip instability. Universal primary ultrasound screening has been adopted in some European countries, but enthusiasm for this new technology has been tempered by the subsequent large increases in treatment and follow up. This paper reviews the existing evidence to support the different approaches to screening and describes the research agenda of the MRC working party on congenital dislocation of the hip. A randomised trial of screening is required to evaluate the policy options before ultrasound screening becomes widely adopted within the United Kingdom. The feasibility and acceptability of a trial need to be explored and key issues relating to trial design addressed.