1. Large artery dilatation may be produced by angiotensin-converting enzyme inhibition in hypertensive subjects independently of blood pressure reduction. The resulting increase in arterial compliance may be due to both blood pressure reduction and to arterial smooth muscle relaxation. 2. In healthy volunteers and in hypertensive subjects, dosages producing large artery dilatation seem to be even higher than those causing arteriole dilatation with the resulting blood pressure reduction. 3. It may be important to consider such findings for the remodelling of the cardiovascular system produced by angiotensin-converting enzyme inhibition.