Purpose: Developmental dysplasia of the hip (DDH) increases the risk of secondary degenerative changes and subsequent total hip arthroplasty. The postoperative quality of life in patients with DDH who have been born and grown with this disability and adapted to it during the life, is one of the most challenging issues. This study aimed to compare the quality of life of patients with DDH before and after total hip arthroplasty (THA) operation. 
Methods: This research has a quasi-experimental/interventional design. A group of 20 patients with DDH, who underwent THA operation in Akhtar and Shafaya Hyaiyan hospitals, were evaluated before operation and 6 months after it using SF36 quality of life questionnaire. 
Results: Findings showed significant improvement in all SF-36 subscales scores, including physical function, role physical, role emotional, vitality, mental health, social function, bodily pain, general function, and general health as well as total score (P=0.002). SF-36 mean(SD) scores before and after surgery was 27.41(22.75) and 79.12(28.03), respectively.
Conclusion: THA operation improves the quality of life of patients with DDH