Monohydroxy-gamma-linolenates and arachidonates were oxidized in the presence of alpha-tocopherol and free radical initiators at 37 degrees C. The dihydroxylinolenate products were analyzed and identified by use of a combination of liquid chromatography, mass spectrometry, and NMR techniques. A mechanism for the formation of the dihydroxylinolenates is proposed based on product analysis of oxidations using varied concentrations of alpha-tocopherol. The mechanism for monohydroxyarachidonate oxidation is the same as that of monohydroxylinolenates. However, arachidonate diol analysis is more complicated because of the formation of additional regioisomers that are a result of the parent arachidonate possessing multiple bisallylic hydrogens.