The aim of this study was to investigate the safety of one-stage bilateral open reduction using the anterior approach in the treatment of patients with bilateral Tonnis Type III and IV Developmental Dysplasia of the Hip (DDH). Forty-six patients were retrospectively evaluated. Thirty-eight were female, eight were male. The mean age was 16.63 (11-29) months. The mean follow-up period was 27.18 (12-65) months. The mean hospitalization period after surgery was 1.91 (1-5) days. The mean pre-operative hematocrit level was 35.14% (28.1-44.1) and the mean pre-operative hemoglobin level was 11.75 g/dl (9.3-13.6). The mean post-operative hematocrit level was 32.54% (26.7-40.4) and the mean post-operative hemoglobin level was 10.80 g/dl (8.78-12.3). None of the patients required blood transfusion. The mean anesthesia duration was 133.30 (95-180) minutes, and the mean operation duration was 107.58 (70-145) minutes. According to the modified scoring system by Trevor et al, excellent results were obtained in 66 hips of 46 patients (71.8%), and good results were obtained in 26 hips (28.2%). Twenty two hips (23.91%), which developed acetabular dysplasia in the follow-up period required a secondary acetabular intervention. According to the Kalamchi and MacEwen classification, Type I avascular necrosis developed in ten hips, Type II in one hip, and Type IV in two hips.