The researchers randomly assigned 9193 patients to receive either losartan or atenolol. Of these patients, 6886 had no previous heart, brain, or peripheral vascular disease. The patients and their doctors did not know who received which drug. Patients' blood pressures were taken regularly. If blood pressure levels were greater than 140/90 mm Hg, higher doses of losartan or atenolol or additional antihypertensive drugs were used. Patients were followed for about 5 years. During that time, the researchers routinely checked for complications, such as heart attacks and strokes.