As effective treatment interventions have increased survival rates, there has been greater awareness that many brain tumor patients experience cognitive dysfunction despite adequate disease control. Cognitive difficulties often have an impact on quality of life and interfere with the patient's ability to function at premorbid levels. A review of the literature indicates that whole-brain radiotherapy alone or in combination with chemotherapy results in more pronounced cognitive dysfunction than either partial radiotherapy or chemotherapy alone. Antiepileptic drugs and corticosteroids may also disrupt cognitive functioning. The cognitive domains suggested to be sensitive to treatment-induced cognitive dysfunction include attention and executive functions, memory, and psychomotor speed. Recent studies have proposed guidelines for the neuropsychological assessment of brain tumor patients and emphasized the importance of including sensitive measures in future clinical trials. This approach will increase our understanding of the incidence of cognitive dysfunction in this population and provide relevant information about therapy-related neurotoxicity.