To compare the cost effectiveness of the angiotensin II receptor blockers (ARBs) olmesartan medoxomil, losartan, valsartan and irbesartan for the treatment of hypertension, from the perspective of a US managed care setting. The evaluation was based on a recently completed, prospective, randomised, double-blind clinical trial comparing the antihypertensive efficacy of these agents. Differences in diastolic blood pressure reductions among the comparative agents were used to estimate reductions in the annualised risk of cardiovascular (CV) and cerebrovascular events using the Framingham model. These annualised risks were translated into reductions in healthcare expenditures associated with treating CV events covered by managed care in the US. Data sources included: the recently published clinical trial of ARB antihypertensive efficacy, the Framingham Heart Study and a managed care database. Actual reimbursed amounts were used. Based on antihypertensive efficacy data versus irbesartan, the use of olmesartan medoxomil is expected to reduce the number of new cases of CV disease, resulting in a first-year reduction in cost in a cohort of 100,000 patients of 906,000 US dollars. Similarly, a reduction in new cases of coronary heart disease (CHD) resulted in a cost reduction of 701,000 US dollars; a cost reduction of 196,000 US dollars for fewer myocardial infarctions (MI); and a cost reduction of 28,000 US dollars for fewer strokes. Over 5 years, these estimates increase to 5,410,000 US dollars for fewer cases of CV disease; 3,975,000 US dollars for fewer cases of CHD; 1,430,000 US dollars for fewer MI; and 497,000 US dollars for fewer strokes. Compared with valsartan, the use of olmesartan medoxomil is estimated to reduce by 3,397,000 US dollars the expected cost of treating a cohort of 100 000 patients in the first year for fewer cases of CV disease; by 2,426,000 US dollars for fewer cases of CHD; by 565,000 US dollars for fewer MI; and by 124,000 US dollars for fewer strokes. Over 5 years, these estimates increase to 16,231,000 US dollars for CV disease; 11,955,000 US dollars for CHD; 4,505,000 US dollars for MI; and 1,741,000 dollars for stroke. Compared with losartan, the estimated reduction in first-year cost is 2,969,000 US dollars for CV disease for the cohort of 100,000 patients; 2,163,000 US dollars for CHD; 732,000 US dollars for MI; and 124,000 US dollars for stroke. Over 5 years, these estimates increase to 15,149,000 US dollars for CV disease; 11,107,000 US dollars for CHD; 4,057,000 US dollars for MI; and 1,437,000 dollars for stroke. Based on comparative antihypertensive efficacy data, treatment of hypertensive patients with olmesartan medoxomil instead of the other leading ARBs has the potential to reduce overall cost of medical care in a US managed care setting.