✓ Seventeen cases of aneurysmal bone cyst of the spine are reported. Clinical manifestations, methods of investigation, differential diagnosis, treatment, and pathogenesis are discussed. The condition is essentially a benign lesion, affects a young age group, and grows rapidly, often producing a paravertebral mass. Occasionally it becomes acutely exacerbated, causing irreversible damage to the spinal cord. For these reasons, prompt diagnosis and timely treatment are important. Excision of the lesion is the treatment of choice but, if not feasible, thorough curettage and radiotherapy not exceeding 2000 rads are indicated. With a two-stage operation, excision of the lesion is often possible, and the stability of the vertebral column is assured with bone-graft fusions.