Due to poor penetration of bone, ultrasonic techniques have not been popular in orthropedic procedures. Since they are non-invasive and are not associated with a radiation hazard, their application in the diagnosis of congenital hip-joint dislocations merits investigation. Methods are presented in Part I which should enable the experienced investigator to make the diagnosis and avoid flash interpretations. In Part II, the practical results of these techniques over an 18 month period are presented and discussed. The small size of the object under examination and the, in general, poor resolving power of ultrasonoscopes constitute the major difficulties encountered when using ultrasonic diagnostic devices. The fact that these methods are harmless to the patient, economical, simple to perform, and noninvasive, make them attractive diagnostic tools for screening infant hip-joints congenital luxations.