A case is presented of a 5.5-year-old girl admitted with acute mastoiditis and facial nerve palsy. The final diagnosis of leukemic infiltration of the mastoid bone, middle ear and VIIth cranial nerve was made only after surgery and histological examination. Similar cases described in the English literature are reviewed and treatment is discussed. Chemotherapy or combined chemo- and radiotherapy are the treatment of choice in known leukemic patients without symptoms of superimposed infection of the ear or the mastoid process. Surgical management is restricted to cases in which tissue for histological diagnosis is required or drainage of acute infection is needed.