Aim: High plasma cholesterol levels, mainly LDL is a widely recognized major risk factor for Coronary Heart Disease( CHD). According to the epidemiologic studies findings, people from the Mediterranean countries, have lower CHD rates than other countries, in these countries the usual diet is high in olive oil. The present study compares the effects of cholesterol-enriched diet with or without adding olive oil on serum Lipoproteins, lipid peroxidation, and atherosclerosis development. Methods: Twenty Dutch male rabbits were categorized into four groups (one group as Control, and others as Experimental ). They received one of Standard (I), Olive oil rich (II), Cholesterol – rich (III), and Cholesterol + Olive oil (IV) diet for Twelve weeks. Fasting blood samples from the heart were collected at the beginning, and the end of the experimental period. Results: Means of serum lipids were not significantly different at the beginning of the experimental period. After intervention, significant differences were showen in total cholesterol, HDL-C, triglyceride and MDA between groups. The comparison of III and the IV groups showed a higher mean of MDA in group III (P< 0.001). Any aortic lesion was not observed at I and II groups. Aortic lesions in IV group showed a significantly lower degree than group III (p=0.02). Conclusions: These findings showed the preventive effect of olive oil against atherosclerosis development which is independent of plasma lipoprotein effect, and suggested that probably olive oil acts on arteries directly.