Despite the existence of a well described, succinct pathological grading system for gliomas, tumour behaviour between individual patients varies widely. In addition, predictors of response to treatment in glioblastoma multiforme are lacking. The majority of chemotherapeutic agents currently employed exert their effect on DNA. As our understanding of DNA repair mechanisms improves and predictive markers are elucidated, this may allow treating clinicians to individualise treatment based on molecular markers. This review examines important DNA repair mechanisms and their application to glioblastoma multiforme. By improving understanding of these mechanisms, and particularly the variations that occur between tumours and individuals, it may be possible to adapt treatment to maximise effectiveness and minimise toxicity.