The Trial of Antihypertensive Interventions and Management was a multicenter randomized, placebo-controlled trial designed to assess the effectiveness of various combinations of pharmacologic and dietary interventions in the treatment of mild hypertension (diastolic blood pressure 90-100 mmHg). The primary outcome was blood pressure change between baseline and 6 months. The study consisted of a 3 X 3 factorial design wherein participants were randomly allocated to nine drug-diet treatment groups. Drugs included placebo, diuretic, and beta-blocker. Diets were usual, weight loss, and low sodium/high potassium. The basic strategy was to address clinical questions of interest by comparing mean blood pressure changes of selected drug-diet combinations. This paper describes the study including experimental design, sample size considerations, statistical analysis, organizational structure, and baseline findings.