The method is described of multistep pathomorphological examination of biopsy material obtained by stereotactic procedures from brain tumours. In the analysis of 260 biopsies the possibility was assessed of intraoperative cytological examinations confronting the results of these examinations with those of final histological and immunohistochemical investigations. Attention is called to the difficulties in the evaluation of material derived from stereotactic biopsies and to the cause of possible diagnostic errors. It is concluded that the combination of the results of cytological examination of smears and histological examination of paraffin slides makes possible establishing of full pathomorphological diagnosis with determination of tumour type and its malignancy degree in 90.7% of cases. On most cases cytological intraoperative examination had the greatest influence on therapeutic management. In the confrontation of these examinations with histological examinations a high proportion of correct cytological examinations was found (76.6%). Owing to the possibility of application of all techniques of morphological diagnosis, stereotactic biopsy is a reliable method in the diagnosis of brain tumours.