Abstract: Objective To investigate the clinical efficacy and surgical strategy of cementless total hip arthroplasty (THA) in patients with ankylosing spondylitis (AS) combined with flexion contracture deformity. Methods Eighty-two hip-joint lesions in 41 patients who admitted to our hospital from August 2011 to July 2012 were performed cementless THA. The average follow-up period was 24.6 months (range 21-32 months). The degree of pain, deformity, motion and function of hip-joint were compared before and after surgery. The function of hip-joint was evaluated by Harris scoring system. Results The preoperative flexion contracture deformity of hip-joints was improved from 72.4º (64.8º-81.5º) to 20.7º (8.6º-36.4º) (P＜ 0.01) after surgery. The motion and score of hipjoints before surgery were improved from 2.7º (0º-5.8º) to 84.5º (78.7º-104.5º) (P＜ 0.01), 25.7 to 78.1 (P＜ 0.01) after surgery, respectively. No looseness and dislocation of the prosthesis was showed on final follow-up X-Ray examination. Conclusion Cementless THA is the most effective treatment strategy to relieve pain and restore function for hip-joint lesions due to AS.