Background Ossification of the ligamentum flavum (OLF) has been widely recognized as one of the main causes of thoracic spinal canal stenosis and thoracic myelopathy.Decompression is the only effective strategy for treating thoracic myelopathy caused by OLF.The purpose of this study was to describe the clinical outcomes of computer-assisted minimally invasive spine surgery (CAMISS) for posterior decompression in patients with thoracic myelopathy caused by OLF.Methods In all cases,the surgical procedure was performed with the assistance of an intraoperative three-dimensional navigation system.Decompression of the spinal cord was performed with a high-speed drill; the supraspinal ligaments and spinous process were partially preserved.The outcomes were evaluated by a modified Japanese Orthopedic Association (JOA) scoring system and recovery rates.Results The mean duration of follow-up for the 14 cases was 3.9 years.All patients experienced neurological recovery,the mean JOA score improving from 6.1 points preoperatively to 8.6 points at final follow-up and the mean rate of recovery being 52.7％ (excellent in two cases,good in eight,fair in three,and unchanged in one).Conclusion CAMISS is a safe and effective procedure for resection of the OLF in the thoracic spine.