Phospholipid and fatty acid composition of human brain tumors is presented. The white matter contains a greater amount of phosphatidylinositol and a very low level of lysophosphoglycerides, as compared to the grey matter. Glioma and meningioma tumors contain a greater amount of phosphatidylinositol, sphingomyelin, and lysophosphoglycerides, as compared to normal cortex tissue. A significant rise in oleic, linoleic and arachidonic acid content in tumor tissue was observed. It is suggested, that changes in lipid composition, may play a role in structural and functional membrane perturbations in neoplastic cells.