<span style="font-family:Verdana;line-height:1.5;">In this communication, we report our experience with a case of thoracic vertebral fracture which was treated by balloon kyphoplasty and which later developed an infection at the fracture site, causing treatment difficulty. The patient was a 74-year old female with a history of remitting seronegative symmetrical synovitis with pitting edema (RS3PE) syndrome as well as diabetes mellitus. She had been diagnosed with mycoplasma pneumonia as well as a fracture of the T12 vertebral and was admitted to the Department of Internal Medicine to receive medical/non-surgical treatment. Medical treatment was carried out and the pneumonia symptoms improved but getting out of bed was impossible due to the continuing of back pain. Therefore, T12 balloon kyphoplasty was performed in order to allow for early ambulation. Back pain started to improve immediately after surgery, but at 2 months after surgery, the back pain relapsed, and fever developed. Imaging tests revealed a vertebral osteolysis of T11-T12 and, as a measure against vertebral collapse due to postoperative infection or osteomyelitis of the thoracic spine, the feasibility of balloon kyphoplasty was considered. Antibiotic treatment was carried out, and when findings showed that the infection had resolved, posterior fusion (T9-L2) was performed using percutaneous pedicle screws. When balloon kyphoplasty for the treatment of a vertebral fracture is performed in an immunocompromised patient early after injury, the treatment needs to be chosen carefully, and the possibility of a latent vertebral osteomyelitis should be kept in mind.