TOMHS I enrolled 902 men and women to determine the feasibility of a larger trial. Participants were randomized in a double-blind manner to one of six treatment groups and within two strata. Stratum I was for participants not on antihypertensive drugs and Stratum II for those on antihypertensive drugs at initial screening. There were six treatment arms: placebo, a diuretic (chlorthalidone), a beta-adrenergic blocking agent (acebutolol), an alpha blocker (doxazosin mesylate), a calcium antagonist (amlodipine maleate), and an angiotensin converting enzyme inhibitor (enalapril maleate). All participants received a lifestyle intervention program that included reduction of sodium chloride and alcohol intake as well as weight reduction and increase in physical activity. All participants were followed for at least 48 months, with an average of 54 months. The primary endpoint was lowering of blood pressure. The treatments were also compared for effects on blood chemistries including lipoproteins, echocardiographic left ventricular mass, ventricular ectopic activity and ST-T changes of ischemia as measured by ambulatory ECG monitoring, side effects, and quality of life. Randomization took place between October 1986 and March 1988. Active follow-up ended in March-April 1992. Data analysis ended in May 1994.