Total fatty acids processed from whole brain samples removed at autopsy from men and women, 26-87 years of age, were esterified, the methyl esters analyzed by gas chromatography, and the respective profiles deduced. In the study of the effect of age and sex in relation to the fatty acid levels, regression analysis was applied to smoothened data to take care of extraneous effects or variables. Toward this end, five age groupings were formed and the regression relationships explored for each group per sex. Generally, the saturated homologs occurred in higher amounts among males of advancing age but decreased with age among females. This effect stemmed from the even-carbon acids. For the unsaturated fatty acids, the reverse behavior appeared evident. For the prominent acids, 16:0 and 18:0, the differences were moderately significant for cases 50 years and older, for 18:2, significance based on either sex was noted with all age groups.