The principal objective of this study was to elucidate novel routes of synthesis of hormonal substances in the brain which use the polyunsaturated fatty acid, docosahexaenoic acid (C22:6) as precursor. This fatty acid is the major unsaturate in aminophospholipids of brain, retina and testes. Previous work has defined important functions for these lipid species for protein fluidization since they selectively associate with membrane proteins. The results described in this report of their metabolism provide an understanding of a second major function for hexaenoic lipids in the brain. When rat brain is incubated with exogenous C14-22:6, several oxidized products are enzymatically formed. Using HPLC for separation and purification and mass spectrometry for analysis of structure, we have determined that mono- and trihydroxy- derivatives of 22:6 are formed. The synthesis of these leukotriene-like products is increased by low concentrations of ethanol.