Giant cell tumours (GCT) are relatively rare neoplasms, most often benign. They are characterized by their local aggression. We report two observations of GCT, the spine in a 51-year-old woman and a 14-year-old boy. They were revealed by spinal pain and cord compression for the second observation. Computed tomography and magnetic resonance imaging showed osteolysis of the body and vertebral arch of L5 for the first and a process affecting the vertebral body and medullary canal of T6-T7 with spinal cord compression for the second case. The diagnosis was confirmed by histological examination in two cases. An external radiation at a dose of 45 Gy on L4, L5 and the sacrum was made in the first case and the dose of 40 Gy on the vertebrae of T4 to T9 and an additional 6 Gy on T5-T8 in the second case. The patients are alive without progress with five years and 18 months follow-up, respectively. Radiation could be proposed as a standard treatment for patients with incomplete excision or where surgery would induces functional deficits.