Acute biphenotypic leukaemia (BAL) is an uncommon haematological malignancy with features of myeloid and lymphoid origin and poor overall prognosis. We report a 68-year-old man who presented with rapidly progressive upper thoracic spinal cord compression secondary to an extradural lesion. A T2–3 decompressive laminectomy with tumour excision was performed. Histopathology confirmed the diagnosis of acute biphenotypic (B/myeloid) leukaemia. The patient had only minor post-operative improvement in pyramidal lower limb weakness. He succumbed to the disease three months post-diagnosis after failing induction chemotherapy. While central nervous system involvement with acute leukaemia is well recognised, this is the first reported patient with spinal cord compression secondary to this leukaemia subtype.