AbstractLipoproteins have an important influence on arterial tissues. High levels of low density lipoproteins (LDL) may inhibit arterial function in terms of the release of nitric oxide from the endothelium. This inhibition is enhanced by the oxidation of these lipoproteins which may occur during the development of atherosclerosis. Many of these effects are due to lipid oxidation products. The impairment of the release of nitric oxide and vasodilatation may be partially attenuated by antioxidants. LDL may also enhance the activity of blood platelets, especially when they are mildly oxidized. Oral administration of antioxidants may decrease the activation of platelets to a limited extent. Lipid peroxides may play a role in these processes.