【Abstract】 Objective To summarize techniques of the total hi p arthroplasty (THA) in the treatment of developmental dysplasia of the hi p (DDH) with severe osteoarthritis in adults. Methods From March 2000 to January 2006, 24 patients (27 hips) with DDH were treated by THA with an cementless cup. There were 7 males and 17 females, withthe average age of 49.6 years (ranging from 26 years to 63 years). Unilateral DDH occurred in 21 patients and bilateral DDH occurred in 3 patients. Based on the Crowe classification, there were 16 hips in 15 patients of type I, 4 hips in 4 patients of type II, 4 hips in 3 patients of type III, 3 hips in 2 patients of type IV. Except for 3 patients with bilateral DDH, the other patients’ ill lower l imbs were 2-7 cm shorter than the healthy lower ones. Results All the patients were followed up from 9 months to 6.5 years and no one had infection, dislocation, femur fracture and so on after the operation. In 18 patients, the pain was completely rel ieved and the function of the hip joints was good. After the gluteus medius exercise, the claudication of 3 patients after the operation disappeared. In 3 patients, the ill lower l imbs were more than 1 cm shorter than the healthy lower ones and the other patients’ ill lower l imbs were less than 1 cm shorter than the healthy lower ones. Two patients’ lower l imbs were been lengthened 4-5 cm. All the patients’ sciatic nerves were not injured. The Harris scores were 46.5 ± 7.2 preoperatively and 84.0 ± 5.7 postoperatively (P lt; 0.05). Conclusion THA with deepening the medial wall of the acetabulum at the true acetabulum and choosing small cementless cup in adult could obtain favorable results.