OBJECTIVES: ARBs were introduced into the UK antihypertensive drug market with conflicting data on their relative effectiveness compared to other classes, which offered lower cost alternatives. The study aim was to determine patient-level characteristics of ARB prescribing patterns and how these changed over time since the first ARB market launch December 1994. METHODS: The study population was identified from the Health Improvement Network (THIN) database, an electronic medical record dataset of patients seen by general practitioners in the UK. Patients who received an oral drug approved for hypertension treatment at any point in time from 1995 through 2003 were included. The multinomial logit model was applied to two time periods to predict the likelihood of receiving an ARB prescription compared to other antihypertensive drug classes, after controlling for patient characteristics. A time dummy tested for changes between the time periods. RESULTS: Immediately after the first ARB introduction (1995-1997), 0.25% (N=537,309) of the study population was allocated to ARB therapy. This rose to 6.22% (N=803,981) for the more recent time period (2001-2003). In the early time period, patients with high blood pressure readings and patients seen by a Cardiologist were more likely to receive prescriptions for ARBs than other antihypertensive classes. This did not persist for the more recent time period. Over time, prescribing antihypertensive drugs for patients with diabetes shifted away from all classes (P<0.01), except the angiotensin converting enzyme inhibitor (ACEi) class (P=0.6334), towards ARB prescribing. For patients with heart failure, there was a statistically significantly shift away from prescribing ARBs towards the beta-blocker and “Other” classes. In general, patients with diabetes or heart failure were more frequently prescribed ACEi than ARB therapy. CONLUSIONS: ARBs were prescribed cautiously in the UK and ARB prescribing patterns altered over time as new safety and effectiveness evidence emerged.