The Dega acetabuloplasty is considered to be safe and effective in the treatment of hip pathologies, but the number of clinical follow-up series in the literature is not sufficient. The aim of our study was to identify the alterations in acetabular development in 35 patients (43 hips) with developmental dysplasia of the hip who were treated with Dega acetabuloplasty. This study is a retrospective review of 7 years of one surgeon's experience with Dega acetabuloplasty performed between May 2002 and January 2010. A total of 35 patients (43 hips) were evaluated, with an average of 58 months (range 25-108 months) of follow-up. Dega acetabuloplasties that were performed for neuromuscular or other conditions and patients who had a follow-up period of less than 2 years were excluded. Open reduction was performed and femoral shortening or varus osteotomy was added whenever the surgeon considered it necessary. The preoperative mean acetabular index (AI) was 35 degrees (range 27-53 degrees), and the mean age of operation was 35 months (range 18-65 months). The mean AI in the early postoperative period was 20 degrees (range 10-34 degrees). At the last follow-up, all patients were pain-free and had unlimited physical activity with no limp, with an improvement in AI to 13 degrees (range 5-23 degrees). An improvement of 7 degrees was observed in AI within the follow-up period. The maximum improvement was 17 degrees and occurred within an 83-month period. In 42 of 43 (98%) of the hips, the AI improved; in one of 43 (2%) of the hips, it remained unchanged and in none of hips did the AI worsen over time. This study is one of the largest series in the English-language orthopedic literature to report that Dega osteotomy is effective in improving the AI and femoral coverage, and that the index further improves over the course of the follow-up period. J Pediatr Orthop B 22:91-95 (c) 2013 Wolters Kluwer Health vertical bar Lippincott Williams & Wilkins.