To investigate cl inical outcomes of percutaneous kyphoplasty with balloon in the treatment of severe osteoporotic thoracic vertebral compression fracture (SVCF). Methods From May 2006 to July 2007, percutaneous unilateral kyphoplasty with single balloon was performed in 7 vertebras of 6 SVCF patients, with 2 injured vertebras in 2 malesand 5 in 4 females, who were from 64 to 83 years old. The injured vertebras included 1 in T5, 2 in T8, 3 in T10 and 1 in T12 and the compression rates were 60% to 75% in 5 vertebras and gt; 75% in 2 vertebras. All the injured vertebras were old fractures and caused severe back pain, but without any neurotic symptoms and signs. The visual analogue scale (VAS) ranged from 6.5 to 9.0, 7.7 on average. The posterior vertebral walls were all intact in all patients under CT scan. The balloon was inset into the vertebra through pedicle of vertebral arch by percutaneous puncture under the guidance of C-type arm X-ray unit. The balloon was then extended to restore the vertebral body which was filled with bone cement later. The average volume of cement required was 3.5 mL (2.6 to 4.4 mL). Results The pain was alleviated or completely rel ieved after the operation. The mean vertebral body height restoration was 9.7% ±1.4% on the anterior border. Two cement leakages were found on X-ray. One month after the treatment, the VAS was from 0 to 2.45, 1.32 on average, and there was significant difference compared with preoperation (P lt; 0. 05). Three months after the treatment, the VAS was from 0 to 3, 2.13 on average, and there was no significant difference compared with 1 month after the treatment (P gt; 0.05). It was not found that the injured vertebras were compressed or deformed, and no new compressed fracture was found in consecutive vertebras. Conclusion Unilateral posterior-lateral puncture kyphoplasty with single balloon can rel ieve the pain and restore part of the vertebral height effectively with better outcomes.