PURPOSE OF THE STUDY The purpose of the retrospective study was to analyse the success rate and safety of overhead traction in treating decentered hip joints. In patients treated strictly non-operatively, i.e. with no open reduction and no operative management of residual dysplasia performed, acetabular development was assessed once they have reached the skeletal maturity. MATERIAL AND METHODS The restrospective study included a total of 40 patients treated by overhead traction in the period 1999-2002 for developmental dysplasia of the hip (ultrasound classes III.A, III.B, IV according to Graf classification). The study group consisted of 35 girls and 5 boys. 10 patients were affected bilaterally. The two-phase traction was applied during the hospital stay and concluded by arthrography of the treated hip joint under general anaesthesia to confirm its concentric reduction and stability within the safe zone. To allow healing, bilateral plaster hip spica cast was applied for 6 weeks, followed by Pavlik harness. The Salter diagnostic criteria were used for avascular necrosis. The acetabular development in non-operatively treated patients was assessed after reaching skeletal maturity according to the Severin criteria. The radiographic parameters (center-edge angle of Wiberg, Sharp angle, Tönnis angle, acetabular coverage of the femoral head, grade of osteoarthritis according to Tönnis classification) were statistically compared with the control group of 18 healthy contralateral hip joints. RESULTS By overhead traction the closed reduction of 43 hips (86%) was successfully achieved. In the group of hips with successful closed reduction, avascular necrosis of the femoral head developed in 1 case (2.3%). In preschool age, surgical correction of the residual acetabular dysplasia or subluxation was performed in 7 hip joints (16%) in the group of successful closed reductions. According to the Severin criteria for the evaluation of radiographic results, the findings were favourable (Severin Ia, Ib) after reaching the skeletal maturity in 29 of 43 (67%) hip joints, in which closed reduction was originally successfully achieved. No statistically significant difference in the studied radiographic parameters was found between the group of treated hip joints and the control group. DISCUSSION Despite the general consensus regarding the beneficial effects of early diagnosis of developmental dysplasia of the hip in the form of better treatment outcomes and reduced risk of complications in the world literature, the authors of individual studies do not agree as to the used treatment method, timing and duration of treatment. Neither they agree as regards the importance of traction therapy in decentered hip joints. Our study brings information primarily on the acetabular development in patients treated by traction, commenced early, namely before the age of 6 months. CONCLUSIONS Based on our experience, the overhead traction is an efficient treatment option in managing decentered hip joints (ultrasound types III.A, III.B, IV according to Graf). It is a safe method provided the safe zone principles are adhered to during the traction treatment as such as well as during the retention phase with the plaster hip spica applied. Development of the treated hip joint shall be regularly followed up until the skeletal maturity is reached. Key words: developmental dysplasia of the hip, closed reduction, overhead traction.