The quality of life of patients treated for brain tumours and the length of survival are important factors making possible the evaluation of treatment effectiveness. Changes of life quality evaluated by the Karnofsky scale were analysed in a group of 56 patients who have received combined treatment for poorly differentiated supratentorial gliomas. Life quality changes were evaluated after completion of surgical and radiological treatment in relation to preoperative status. The influence of various clinical factors on life quality changes was evaluated. Surgical treatment and tumour site had a significant effect on the stabilization or slight improvement of life quality. The direction and extent of life quality changes were related to surgery, with further change after radiotherapy.