A battery of psychologic tests was administered to 32 patients, aged from 26 to 61 years, who had survived 2 years or more after treatment with surgery and radiotherapy for supratentorial gliomas (18 low grade and 14 high grade) without evidence of recurrent tumor on MRI. Two groups were identified. A first group of 17 patients had neuropsychologic scores similar to estimated premorbid level (group I). A second group of 15 patients had abnormal neuropsychologic scores, lower that their estimated premorbid level (group II). In comparison with "normal" patients, those with abnormal neuropsychologic scores were older at the time of treatment, had a lower post-operative Karnofski Performance Status, a longer delay between surgery and the date of the tests and more often had left sided lesions. Comparison of Karnofski Performance Status between the post-operative time point and the date of neuropsychological evaluation did not show a significant change over time in groups I and II except in 3 patients who experienced progressive deterioration. Vigorous treatment of gliomas with surgery, radiotherapy and sometimes chemotherapy does not induce a substantial cognitive dysfunction in about half of the long term survivors (53%). Cognitive dysfunction is identified in the other half that could be related to post-operative sequelae (due to the tumor itself or to surgery) and/or to radiotherapy- and chemotherapy-induced delayed toxicity.