Glioblastoma multiforme is a particularly malignant form of primary brain tumor. This cancer represents 12-15% of all brain tumors. Despite advances in neurosurgery, radiation and chemotherapy, the average survival rate is only from 12.1 to 14.6 months. Glioblastoma multiforme is characterized by its diverse histological and cellular features. Like other malignant tumours, it is formed in a multi-stage process of somatic cell transformations, accumulating several genetic disorders. The last decade was a period of particular interest in stem cells. These cells have so far been identified in a variety of primary tumours in the brain. They are probably responsible for the recurrence and progression of cancer. Given the current state of knowledge, it is likely that modifications to the previously used morphological classification of tumours of the CNS will be made by the WHO, as well as the extension of its molecular criteria. In particular, such strategies are awaited for Glioblastoma multiforme--the most malignant primary tumor of the central nervous system, with so far very poor prognosis.