The clinico-neuropathological report is given of a glioblastoma multiforme with primary site in the cerebellum. The patient presented clinically with Wallenberg's syndrome; morphological investigations revealed the tumor partly invading the dorsolateral region of medulla oblongata. There are some reports of Wallenberg's syndrome not caused by vascular stenosis or occlusion, but by metastatic tumors in the lateral medullary region. The present report is the first of a cerebellar glioblastoma causing the peculiar brainstem syndrome.