Abstract:[Objective] To explore the reasons for revision of upper cervical instrumented fusion, and to evaluate the clinical efficacy of revision surgery. [Methods] A retrospective study was performed on 16 patients who underwent revision surgery for failed upper cervical fu- sion in our department from 2017 to 2021. The reasons for revision, as well as the clinical and imaging consequences of revision surgery were evaluated. [Results] The reason for revision surgery proved improper reduction of atlantoaxial dislocation in 5 cases, nonunion of bone graft in 5 cases, incomplete decompression in 3 cases, tumor recurrence in 2 cases and infection in 1 case. All the 16 patients had revision surgery performed smoothly, with operation time of (216.25±23.34) min, the intraoperative blood loss of (406.25±103.08) ml, and the good incision healing. Except one patient who suffered from tumor patient was lost to follow-up, all the patients were followed up for (31.35±8.98) months on a mean. The JOA scores increased significantly (P＜005) , and ASIA grade for neurological function improved significantly over time (P＜ 005) . Radiographically, the head- neck alignment was significantly improved (P＜0.05) , ADI decreased significantly (P＜0.05) , whereas SAC significantly increased after revision surgery compared with those preoperatively (P＜0.05) . [Conclusion] The factors related to revi- sion of upper cervical fusion influence each other in many cases. Reasonable formulation of revision surgical plan and accurate operation do still achieve satisfactory clinical outcomes.