The purpose of the present study is to determine the outcome success of anterior open reduction with Pemberton osteotomy in patients under 18months of age with developmental dysplasia of the hip. We retrospectively reviewed the clinical and radiological results of 27developmentalhipdysplasiapatients under 18months of age(26 girls, 1 boy)who underwentanterior open reduction with Pemberton osteotomy. Bilateral surgery was performed in 18 patients and unilateral in nine patients. At the final follow-up, the clinical results were evaluated according to the McKay's clinical evaluation criteria, the radiological results according to the Severin's radiological evaluation criteria, and the presence of avascular necrosis according to the Kalamchi-MacEwen's classification criteria. We treated 36 hips of 27 patients who were younger than 18months of age (range 10-18months) at the time of surgery and followed up a minimum of 5years (mean 6.5years). At the final follow-up, 34 (94.4%) were assessed clinically as excellent, one hip (2.7%) as good and one hip (2.7%) as fair according to the McKay's clinical classification. Radiological classification revealed that, 97.2% of the hips were Severin Type-1 and 2.8% Severin Type-3. Avascular necrosis was observed in 5 of 36 hips (13.8%). Two hips were assessed as Type-2, two hips Type-3 and one hip Type-4 according to the Kalamchi-MacEwen's classification. We conclude that Pemberton osteotomy with anterior open reduction is useful technique for developmental hip dysplasia treatment of patients under the age of 18months with good clinical and radiological results as well as with low complication rates.