Objective: To report a rare event of a retrograde flow of cement leakage during balloon kyphoplasty and discuss the possible mechanism. Methods:We present a 55-year-old male patient, who underwent a 4-level balloon kyphoplasty for Langerhans histiocytosis that had spread to the spine. With the patient prone under general anesthesia, intrathoracic pressure was raised as a precaution measure to prevent cement embolic complications as a protocol reported elsewhere. Results:During the last vertebral body procedure (L1), cement leakage was noticed to flow downward in a retrograde fashion into the segmental vertebral vein and the procedure was immediately discontinued. Cement leak did not follow the predictable upward blood flow through the anterior or lateral segmental vein into the vena cava, but instead, the cement followed a retrograde downward path into the Batson's vein. No adverse cardiopulmonary effect was observed. Evidence of pulmonary cement embolism was detected in a routine thoracic computed tomography six week later. Conclusion:To our knowledge this is the first case in the English-speaking literature to highlight a retrograde cement intravascular flow most likely as a result of increased intrathoracic pressure.