Despite intensive research, gliomas still lead to death in most cases. The isolation of brain tumour stem cells from gliomas has paved the way for a growing body of evidence suggesting that these cells are responsible for the resistance of gliomas towards conventional therapy. Recent results suggest that the growth of brain tumours can be inhibited by treatment strategies targeting the brain tumour stem cells. Here, the brain tumour stem cell paradigm is described with a focus on tumour stem cell characteristics and the role of this subpopulation of tumour cells in the resistance towards radiation and chemotherapy.