3,4-Dihydroxyphenyl ethanol is a phenolic component of olive oil that inhibits both 12- and 5-LO. The IC50 values for the inhibition of rat platelet 12-LO and rat neutrophil 5-LO are 4.2 and 13 µM, respectively. It does not inhibit, and may actually enhance, COX activity. 3,4-Dihydroxyphenyl ethanol also protects LDL from both biological and chemical oxidation, suggesting a potential mechanism for the protective effects of olive oil against atherosclerosis.