Twelve cases are reviewed of ossification of posterior longitudinal ligament (OPLL) in the thoracic spine for which anterior decompression and fusion were performed. A transthoracic approach was used in 10 patients, and median sternotomy and a transsternal approach were used in one each. The clinical symptoms and the Japanese Orthopaedic Association (JOA) score improved in 10 patients, whereas they were unchanged in two patients who underwent a revision operation for a previous laminectomy. An anterior procedure that results in adequate decompression of the spinal cord and good spinal stability is recommended for anterior lesions, such as OPLL, which compress the anterior spinal cord at each level of the thoracic spine.