OBJECT The object of this study was to evaluate the efficacy and safety of posterior decompression with kyphosis correction for thoracic myelopathy due to ossification of the ligamentum flavum (OLF) and ossification of the posterior longitudinal ligament (OPLL) at the same level. METHODS Between January 2003 and December 2005, 11 patients (8 men and 3 women) with thoracic myelopathy due to OLF and OPLL at the same level underwent posterior decompressive laminectomy and excision of OLF. Posterior instrumentation was also performed for stabilization of the spine and reducing the thoracic kyphosis angle by approximately 5-15 degrees (kyphosis correction), and spinal fusion was performed in all cases. The follow-up period ranged from 2 to 4 years (mean 2.8 years). The outcomes were evaluated using a recovery scale based on the Japanese Orthopaedic Association classification. The score of each patient was calculated before surgery, 1 year after surgery, and at the final follow-up visit. RESULTS After surgery, the thoracic kyphosis in the stabilization area was reduced from 30.0 +/- 4.02 degrees to 20.8 +/- 2.14 degrees on average. The mean score on the Japanese Orthopaedic Association scale improved from 3.5 +/- 1.69 preoperatively to 8.5 +/- 1.63 at the final follow-up, with a recovery rate of 68.0%. The results were good in 9 patients and fair in 2 patients. Postoperative MR imaging showed that the spinal cord was shifted posteriorly and decompressed completely in all cases. Myelopathy was not aggravated in any case after surgery. CONCLUSIONS A considerable degree of neurological recovery was observed after posterior decompression and kyphosis correction. The procedure is easy to perform with a low risk of postoperative paralysis. The authors therefore suggest that the procedure is useful for patients whose spinal cords are severely impinged by OLF and OPLL at the same level.