OBJECTIVE: The model compares -- from a health system's perspective -- the cardiovascular events avoided and costs of six angiotensin receptor blockers (ARBs) in treating mildly-to-moderately hypertensive patients. METHODS: The model considers three potential differences in effectiveness among ARBs: 1) office cuff systolic blood pressure (SBP) reduction; 2) 24-hour ambulatory systolic blood pressure (ABP), and 3) non-compliance. The model uses point estimates of SBP reductions from published trials and meta-analyses identified from Medline and searches of retrieved literature published after 1996. Risks before and after a SBP reduction are estimated using the Framingham cardiovascular risk equation for a hypothetical population of hypertensives. Improved 24-hour ABP confers additional risk reduction, while non-compliance mitigates the reduction depending on each ARB's duration of effect. Drug costs are based on wholesale acquisition cost and average dosing from IMS national estimates for 2003. RESULTS: Over a 5-year timeframe in a representative hypertensive population, ARBs reduce cardiovascular events by 15% to 25% at a yearly cost of $185 to $301 per treated patient or $34,914 to $90,487 per event avoided. The NNT to avoid one event varies from 37.6 for telmisartan to 62.2 for valsartan. Over 5-years, relative to telmisartan, the model predicts 547 (olmesartan) to 1,052 (valsartan) more cardiovascular events per 100,000 hypertensive patients. Telmisartan generates cost savings relative to all ARBs. Assuming no difference between ARBs in cuff SBP reduction, the effects of ABP and non-compliance alone favor telmisartan by 398 to 696 events. The model is sensitive to factors that substantially impact cardiovascular risk like patient age and is more sensitive to ABP differences than to noncompliance. CONCLUSION: Small differences in SBP reduction between ARBs may produce meaningful differences in the number of cardiovascular events avoided. Telmisartan's smooth ABP profile and reduced consequences from non-compliance relative to other ARBs enhance its effectiveness.