【Abstract】 Objective To explore the prevention and treatment of leg length discrepancy after total hip arthroplasty(THA). Methods There were 87 patients who were treated by THA from January 2004 to December 2006, including 36males and 51 females, with the average age of 60.2 years (ranging from 35 years to 78 years). Among these cases, there were 35 of avascular necrosis of the femoral head, 38 of subcapital femoral neck fracture, 4 of femoral neck tumor, 6 of rheumatoid arthritis and 4 of acetabular dysplasia. In 70 cases, the patients had leg length discrepancy, and the legs shortened from 1 cm to 6 cm. Based on the cl inical measurement and radiographic examination, the surgical protocols were designed, the type of the hip prosthesis was chosen, and the neck length of the femoral prosthesis and the position of osteotomy were estimated. By the proper wearing of the acetabula, the best rotation point was found out. The cut plane of the femoral neck was adjusted according to the results of the radiographic and other examinations. The neck length was readjusted after the insertion of the prosthesis so as to achieve intended leg-length equal ization. The discrepancy of the leg length was measured and evaluated after operation. Results Superficial infestation happened in 2 cases 5 days after the operation and was cured by mero-drainage. Luxation happened in 4 cases 4 weeks after the operation, in which 2 cases were cured by operation while the other 2 were cured by manual reduction. All the patients were followed up for 6 months to 36 months, with the average time of 18.3 months. The Harris scores were 34.81 ± 1.36 preoperatively and 91.50 ± 1.87 postoperatively (P lt; 0.05). In the 17 patients with equal legs before the operation, 1 was lengthened 1.5 cm in the leg, while in the 70 patients with shortened legs before the operation, 66 returned to the same length in their legs, and 4 were lengthened or shortened from 1.6 cm to 2.1 cm. The total rate of equal leg length was 94.25%. Conclusion The preoperative measurement, radiographic templating and intraoperative correction, together with postoperative orthopraxy, are effective in prevention and treatment of leg length discrepancy after THA.