1. The organization of a multi-centre randomized therapeutic trial for mild hypertension is described.
2. Particular attention will be paid to the effect of blood pressure lowering on susceptibility to myocardial infarction.
3. It is calculated that screening of around 180 000 subjects will be required, and that approx. 9000 men and 9000 women will eventually enter the treated group, and a similar number be randomly allocated to the control group.
4. Two separate hypotensive drugs, with different modes of action, will be employed in the treated group.