Markers of lipid peroxidative damage have been shown to be elevated in individuals with risk factors for cardiovascular disease, and human atherosclerotic plaque contains products resulting from lipid peroxidation. In particular, the presence of fatty acid oxidation products such as hydroxyeicosatetraenoic acids (HETEs) has previously been suggested as a marker of plaque instability and symptomatic cerebrovascular disease. The aim of the present study was to quantitate the levels of various oxidation products of linoleic acid (HODEs) and arachidonic acid (HETEs), respectively, in human atherosclerotic plaque tissue and assess their level in relation to plaque histopathology, symptoms of cerebrovascular disease and preexisting atherosclerotic risk factors. We also assessed the correlation between the levels of the hydroxy fatty acid compounds and F(2)-isoprostanes, an established marker of in vivo free radical mediated oxidation. Hydroxy fatty acid oxidation products were identified in all histological subtypes of advanced plaque. However, there were no significant differences in levels between the histopathologically classified sub-groups or between patients symptomatic or asymptomatic for cerebrovascular disease. Arachidonic acid oxidation products were significantly higher in those subjects who also had symptomatic peripheral vascular disease. The level of linoleic acid oxidation products was significantly higher in individuals who consumed alcohol on a regular basis. While F(2)-isoprostanes and fatty acid oxidation products were highly correlated (P<0.01), levels of the hydroxy fatty acid compounds were 20-40-fold higher than F(2)-isoprostanes. Chiral analysis of the plaque extracts indicated that all HODEs and HETEs originated primarily from non-enzymatic lipid peroxidation. While our results do not support previous reports that fatty acid oxidation products such as the HETEs are associated with plaque instability and symptomatic cerebrovascular disease, further work is warranted to determine the potential of these compounds as circulating markers for underlying atherosclerotic disease and lipid peroxidative stress.