Ultrasound is the most sensitive method for detecting hip pathology in the first year of life. However, it has been shown that neonatal sonography, or combined sonographic-clinical screening, can cause some over-diagnosis which, when not used properly, can lead to over-treatment. We developed the concept of 'true developmental dysplasia of the hip' on the basis of our experience. Despite the still-growing popularity of Pavlik's method in the treatment of the condition, we were unable to find a study dealing with the relationship between sex, sonographic and clinical pathology, age at the start of treatment, and duration and outcome of treatment. To answer these questions, we assessed patients we had treated using Pavlik's method in a 5-year period at a special developmental dysplasia of the hip clinic. The influence of sex, clinical stability, severity of sonographic pathology and age when treatment was started was assessed according to duration, outcome of treatment and rate of avascular necrosis. In spite of the relatively small number of hips treated in this study, some conclusions can be drawn. The short period of treatment for clinically unstable hips can be surprising. As treatment was started before the age of 14 weeks, the favorable results can be attributed to this fact. There are hips which, according to our theory, will not improve spontaneously to normal; therefore, we believe that our figures reflect the real results of treatment using Pavlik's method. Practically 0% avascular necorosis for all the treated population (only one child had transient avascular necorosis of type 1) is, in our opinion, due to this fact. The high rate of success (98%) can also be attributed to early treatment.