Objective : Kyphoplasty performed in the middle thoracic spine presents technical challenges that differ from those in the lower thoracic or lumbar region due to small pedicle size and angular severity for thoracic kyphosis. The purpose of this study was to evaluate the efficacy of balloon kyphoplasty through extrapedicular approach for the treatment of intractable osteoporotic compression fractures in the middle thoracic spine. Methods : The patients who were performed with one level balloon kyphoplasty through extrapedicular approach due to painful osteoporotic compression fractures at T5-T8 from June 2003 to July 2005 were retrospectively analyzed. Imaging and clinical features were analyzed including involved vertebrae level, vertebral height, Injected cement volume, clinical outcome and complications. Results : Eighteen female patients (age ranged from 60 to 77 years old) were included in this study. The average amount of the implanted cement was $4.2{pm}1.5;cc$. The mean cobb angle and compression rate were improved from $12.1{pm}6.5^{circ}$ to $8.5{pm}7.2^{circ}$ and from 30% to 15%, respectively. The mean pain score (visual analogue scale) prior to kyphoplasty was 7.9 and it decreased to 3.0 after the procedure. Cement leakage to the adjacent disc (2 cases) and paravertebral soft tissues (1 case) were seen but there were no major complications such as pneumothorax, segmental arte 이 Injury, pulmonary embolism, or epidural leakage. Conclusion : Balloon kyphoplasty through extrapedicular approach is considered as a safe and effective in treating the middle thoracic regions with low complication rate.