OBJECTIVES: To understand the differences in reasons behind physicians' antihypertensive therapy choice both across the medication classes and geographies (Europe & US). METHODS: CardioMonitor is a multi-purpose international initiative conducted annually among primary-care physicians (PCPs) and specialists to collect data on cardiovascular patients in the outpatient setting. 2006 data from 5 major countries in Europe (EU5, reported in aggregate) and the U.S for patients with hypertension (HTN) diagnosis and/or antihypertensive use was included in the analysis to evaluate the reasons for choice of three antihypertensive classes (not mutually exclusive) – Angiotensin-II-Receptor Blockers (ARB), Angiotensin-Converting Enzyme Inhibitors (ACE) & Calcium Channel Blockers (CCB). RESULTS: In 2006, 17,220 & 3,530 patients from EU & US respectively satisfied inclusion criteria, with distribution of 3 HTN medication classes being (EU, US; % of patients) – ARB: 31%, 26%, ACE: 44%, 48%, CCB: 23%, 16%. Key reasons (not mutually exclusive) cited by physicians for prescribing antihypertensives were (EU, US): blood-pressure reduction/control (ARB: 98%, 96%, ACE: 92%, 93%, CCB: 89%, 94%), myocardial protection (ARB: 75%, 61%, ACE: 74%, 67%, CCB: 49%, 47%), simple dosing (ARB: 73%, 61%, ACE: 64%, 61%, CCB: 60%, 59%), achieve good patient compliance (ARB: 60%, 47%, ACE: 44%/ 41%, CCB: 44%, 40%), cerebrovascular protection (ARB: 54%, 51%, ACE: 45%, 47%, CCB: 37%, 39%), side-effect-minimization (ARB: 47%, 31%, ACE: 26%, 24%, CCB: 20%, 20%), heart-function improvement (ARB: 33%, 25%, ACE: 44%, 30%, CCB: 18%, 13%), good tolerability (ARB: 46%, 42%, ACE: 40%, 35%, CCB: 35%, 32%), formulary/approved-list (ARB: 15%, 28%, ACE: 25%, 28%, CCB: 20%, 25%) and cost-minimization (ARB: 1%, 6%, ACE: 10%, 18%, CCB: 6%, 9%). CONCLUSION: Cardiovascular conditions, product attributes and patient/health-system issues appear to drive differences in the reasons behind medication choice both within the antihypertensive medication classes and between geographies (EU & US) which may require close scrutiny.