Antibodies against two major gangliosides detected in human brain and brain tumors--Glac2 (GD3) and Gtri2 (GD2)--were tested by immunohistochemistry in an unselected sample of intracranial tumors during the years 1986 through 1991. Two groups emerged as evaluable samples, namely gliomas of different grades and meningiomas. In a pilot series, it was shown that these gangliosides could be visualized in frozen sections of cells of gliomas and meningiomas (as well as neurinomas) and in some structures of the normal brain. It was however not possible in frozen sections to further analyze the cellular or subcellular expression pattern of the mentioned components and paraffin sections with conventional processing were only weakly and diffusely stained. A modified protocol therefore was created that replaced alcohol processing by acetone. With this protocol, interpretable results in paraffin sections were obtained. With this method, 133 single intracranial tumors were investigated as to their immunohistologically detectable ganglioside expression. The most consistent result was that the whole cytoplasm of highly fibrillary (gemistocytic) astrocytes in all grades of gliomas was stained by Gtri2 (GD2) and Glac2 (GD3) with high preponderance of Gtri2 (GD2) expression. In all meningiomas, Glac2 (GD3) had a higher expression than Gtri2. No constant pattern in the other entities emerged. By comparison with GFAP expression in gliomas and vimentin in meningiomas, the colocalisation of gangliosides and intermediary filament proteins is supposed.