The relationship between hypertension and atherosclerosis has been illustrated by epidemiological, clinical and experimental observations. Typical atherosclerotic lesions develop in arterial wall when hypercholesterolaemia is present. Hypertension aggravates these lesions by causing vascular structural changes. In clinical studies, however, the correction of high blood pressure does not decrease the incidence of coronary heart disease. Several hypotheses have been formulated to account for this observation: one is that reversibility of the structural vascular changes induced by hypertension is not complete when the blood pressure is lowered; another is that antihypertensive drugs have a deleterious effect on the vascular wall.