[Introduction - The morphology and immunocytochemical properties of 250 different monolayer cultures derived from various human brain tumor specimens were investigated on purpose to support and complement the neuropatholgical diagnosis. In this study analyses of 124 glioma cases are presented. Methods - The tumor samples were mechanically dissociated and seeded on glass coverslips. After the formation of the monolayer cultures were fixed and stained by May-Grünwald- Giemsa method for the morphological examination. Semi-quantitative immunocytochemical labeling included several different types of mono- and polyclonal primary antibodies using avidin-biotin visualization system. In nine cases of the glioblastomas the sufficient proliferation made possible to establish cell lines from the primary cultures. Results - The glial origin of the tumors was identified in 124 cases based upon the presence of glial fibrillary acidic protein. A negative correlation between the intensity of glial fibrillary acidic protein immunostaining and the grade of tumor malignancy was found. During long-term cultivation of the higher grade gliomas the incidence and intensity of glial fibrillary acidic protein labeled cells was decreasing. Both the vimentin and the neuron specific enolase labeling were in general stronger than the glial fibrillary acidic protein and almost all the cells were stained. The incidence of Ki-67 positive cells increased with the grade of malignancy. Concerning the tumor classification our immunocytochemical results correlated with the routine histopathological examination. Conclusions - On the basis of these results we conclude that monolayer cultures obtained from tumor specimens can support and complement the correct diagnosis of the various human brain tumors.]