The rare occurrence of extra-neural metastases in patients having a tumour of the central nervous system (CNS) could mean that the symptoms of a metastatic lesion are confused with a second pathology. We recently treated a patient with a glioblastoma multiforme who was developing a pancytopaenia at the initial diagnosis. The frequent red cell and platelet transfusions were transitorily active. An extensive radiological investigation and a unilateral iliac bone marrow aspirate and biopsy were performed. Cells immunoreactive to glial fibrillary acidic protein were detected in a specimen obtained from the iliac bone. Post-mortem examination confirmed metastasis to extra-cranial bone and revealed other metastases in lung, mediastinal lymph node and spleen. Therefore, in patients with malignant glioma tumours, bone marrow metastasis, though not common, should be investigated when bone pain or cytopaenia occur.