Abstract: The lipid compositions of 10 different brain regions from patients affected by Alzheimer's disease/senile dementia of Alzheimer's type were analyzed. The total phospholipid amount decreased somewhat in nucleus caudatus and in white matter. The cortical areas that are morphologically affected by Alzheimer's disease, i.e., frontal and temporal cortex and the hippocampus, showed elevated contents of lipid solvent-extractable phosphatidylinositol. Sphingomyelin content was decreased in regions rich in myelin. There was a 20–50% decrease in dolichol amount in all investigated parts of the brain, but no change was seen in the polyisoprenoid pattern. Levels of α-unsaturated polyprenes were decreased in Alzheimer brains. Dolichyl-phosphate content increased in most regions, up to 100%. In both control and Alzheimer tissue almost all of the dolichyl-phosphate was covalently bound, apparently through glycosylation. Cholesterol amounts were highly variable but mostly unchanged, whereas ubiquinone concentrations increased by 30–100% in most regions in brains affected by Alzheimer's disease. These results demonstrate that both phospholipids and neutral lipids are modified in brains affected by Alzheimer's disease/senile dementia of Alzheimer's type.