【Abstract】 Objective To explore the midterm efficacy of superelastic cage implantation for the treatment of osteonecrosisof femoral head (ONFH). Methods From July 1996 to January 1998, 54 patients (75 hips) of ONFH were treatedwith superelastic cage and followed up. Among 54 patients, 5 patients were lost to follow up and 3 patients were dead of myocardialinfarction, renal failure and gastric cancer, respectively. Forty-six patients completed follow up including 32 males and14 females, aged from 21 to 61 with an average of 39 years old. Twenty-nine hips were classified as Ficat Stage Ⅱ and 36 as StageⅢ . Harris score was 58.20 ± 13.82. All patients were evaluated both cl inically and radiographically. Results Postoperatively,forty-six patients (65 hips) were followed up for 86 to 125 months with an average of 8 years and 8 months. Harris score was 80.78 ± 18.77. Twenty-nine hips were rated excellent, 21 good, 2 fair and 13 poor．A total of 76.9% of overall cl inical results were rated as good or excellent. Eight hips (12.3%) with the cage broken were turned to total hip replacement. Radiographicevaluation: 16 hips (24.6%) rated as grade Ⅰ , 34 (52.3%) grade Ⅱ and 15 (23.1%) grade Ⅲ . Conclusion Superelastic cage implantation is one of alternative treatments for ONFH at early and midterm stages. However, long-term follow-up is needed to know whether it is able to cure ONFH and whether cages will be broken as time passes by.