Clinical screening policies for the detection of hip instability or dysplasia of the hip vary internationally. There is general agreement in the Western world that at birth all hip joints should be clinically assessed by the Ortolani and Barlow tests. Currently, there is no consistency regarding who should undertake the examination, the results being worse when inexperienced personnel are used. These clinical tests have poor sensitivity and should be regarded as surveillance, not screening methods. Since the 1980s ultrasonographic assessment of the hip has become a valuable diagnostic tool. However there is continuing controversy on whether this imaging method should be used universally or selectively for 'at risk' and clinically unstable hip joints. Universal ultrasonographic evaluation may result in over-treatment and selective screening may be no better than the best clinical screening programs in reducing the incidence of 'late' irreducible dislocation of the hip. It is generally accepted that all clinically unstable hips should be imaged by ultrasound by static and dynamic methods in order to confirm the diagnosis and to monitor treatment.