This study was undertaken to verify the efficacy of the Pavlik harness in the treatment of developmental disturbances of the hip (DDH) when reduction and stabilization of the hip and conclusion of the treatment are monitored by sonography. With active mother participation, under direct supervision of one consistent orthopaedist, 547 patients (60 with 91 unstable hips; 196 with 232 dysplastic hips, types lib, He, and D; and 291 with 376 dislocated hips types Ilia, Illb, and IV), with an average age of 2.3 months were evaluated. The initial hip flexion in the harness was 60° to 70°, which was adjusted frequently until concentric hip reduction. Sonographic reduction was achieved in 89.7% of the hips in 2 weeks, in 8.3% in 3 weeks, and in 2% in 4 weeks. Sonographic hip stabilization was achieved in 87.4% in 4 weeks, in 9.8% in 5 weeks, and in 2.9% in 6 weeks. Soft tissue landmarks (the cartilaginous roof angle and capsule) were used for assessment of reduction and stabilization, but for conclusion of the treatment, bony roof angle was used as well. Fulltime harness treatment averaged 2.7 months for the whole group (1.4 months for unstable hips, 2.3 months for dysplastic hips, and 3 months for dislocated hips). The harness was abandoned in five patients, four because of mother noncompliance and one because of abdominal surgery. Other serious complications, including avascular necrosis (AVN), did not occur in this study. It was concluded that paying attention to the minute details of treatment with active engagement of the mother in the form of group therapy under direct and consistent supervision of one orthopaedist coupled with sonographic monitoring can ensure satisfactory outcome with a shorter period of treatment in a very high percentage of the cases.