The World Hypertension League (WHL) is an association of antihypertensive leagues, hypertension societies, committees and other national bodies whose aim is to control hypertension in populations. The present paper is the fourth in a series of 'In the Focus Statements' on topics selected for their practical importance to the management of hypertension, addressed to practising physicians. Like the earlier papers, it has been repeatedly and extensively discussed by the representatives of WHL's member organizations' and accepted as a consensus document.