The low levels of CHD morbidity and mortality in Mediterranean regions is partly attributed to dietary factors. Olive oil is a key component of the traditional Mediterranean diet, therefore there has been intensive investigation to determine how olive oil mediates this effect. CHD has a very complex pathophysiology characterised by atherosclerosis, which is the result of aberrant lipoprotein metabolism and a local inflammatory response in the vascular endothelium, and thrombosis. Olive oil is a rich source of monounsaturated fatty acids (MUFA) and antioxidant phenolic compounds. Both of these components mediate the cardio-protective effects associated with olive oil in a number of ways. Traditionally the cardio-protective effect of the Mediterranean diet was ascribed to the hypocholesterolaemic effect of dietary MUFA. Numerous intervention studies have shown that the substitution of dietary saturated fatty acids (SFA) for MUFA significantly reduces total LDL cholesterol concentrations (Mensink & Katan, 1989). More recently, studies have shown that diets