Objective: to estimate the possibilities of cytomorphological and immunocytochemical (ICC) diagnosis during cerebrospinal fluid (CSF) examination in primary and metastatic brain lesions. Subjects and methods. 74 cytological examinations of CSF obtained from 32 patients (11 men, 21 women) were made. The patients’ age ranged from 21 to 68 years. All the patients were divided into three groups according to the nature of central nervous system (CNS) lesions: benign tumors and non-neoplastic lesions, primary and metastatic malignant tumors of the CNS. For CSF morphological evaluation, two cytosections were stained using Leishman’s method. To clarify their cytological diagnosis, 14 patients underwent 18 ICC examinations and 38 ICC assays using monoclonal antibodies to total cytokeratins (panCK), СК7, CD3, CD20, CD45, ER, Ki-67, S100, HMB45, melan A, desmin, EMA, Ber-EP4, p63, S100, Her2/neu, Bcl2, TTF-1, and synaptophysin (Dako) on a Ventana immunohistostainer. Results. The sensitivity of cytology was 47.2%. ICC examination could transfer 7 of the 10 questionable diagnoses to the positive category, which increased the sensitivity of cytological diagnosis to 53.3%. Tumor histogenesis was determined in 7 cases. There were 25 true positive results, 28 false negative results (the section lacked tumor cells when the clinical and morphological diagnosis was verified); 5 tests showed true negative results (this patient category had no malignant CNS tumors). The proportion of uninformative material was 8% (n=6). Conclusion. ICC examination makes it possible not only to transfer the majority of questionable diagnosis to the positive category, which increases the sensitivity of cytological diagnosis, but also to clarify the histogenesis of a tumor. Thus, ICC examinations considerably extend the capabilities of cytomorphology; however, the traditionally small amount of CSF and its low cellularity sometimes limit the application of this method.