Background: Developmental dysplasia of the hip (DDH) is the most common skeletal dysplasia. Two principal methods used in early diagnosis of DDH are clinical examination and ultrasonographic investigation. Dogruel et al. found a low specificity of clinical examination in patients with DDH. Additionally, Kamath et al. stated that ultrasonography performed by a radiologist in routine clinical practice is more reliable than physical examination performed by the average clinician. In clinical practice, the application and assessment of hip ultrasonography are completed by a single person. This assessment determines the followup of the patient. Thus, hip ultrasonography performed on the same person by different individuals under the same conditions will yield a more accurate assessment of the reliability of ultrasonographic assessment of DDH. Although inter-observer reliability was high in many previous studies of ultrasound image evaluation, reliability rates vary among studies of the application of ultrasonography.