A case report of ossification of the posterior longitudinal ligament (OPLL) combined with ossification of the ligamentum flavum, or yellow ligament (OYL), in the upper thoracic spine. To describe a rare clinical entity and its management pitfalls in a patient with upper thoracic myelopathy due to combined OPLL and OYL. A 52-year-old woman developed paresthesia and paraparesis of both legs. One month prior to admission she fell and became unable to walk. She was diagnosed as having upper thoracic myelopathy due to combined OPLL and OYL and was treated by two-stage anterior and posterior spinal decompression. Posterior decompression was achieved first by laminoplasty at C3-Th1 and laminectomy of Th2 and Th3. After posterior decompression, her symptoms immediately and dramatically improved. However, symptoms recurred after she was able to achieve a sitting or standing position. We then performed anterior decompression at Th2, which again improved her symptoms. At two years post-surgery, she is ambulatory with the use of a cane. Upper thoracic myelopathy due to OPLL and OYL was treated by combined 2-staged anterior and posterior decompression. In this case, posterior decompression alone was inadequate to relieve the symptoms of this pathological condition.