OBJECTIVES: To explore the efficacy of Angiotensin Receptor Blockers (ARBs) in reducing blood pressure (BP) compared to ACE Inhibitors in a real-world setting. METHODS: We analysed the records of 16,866 (14,651 ACE Inhibitors and 2,215 ARBs) adult patients with hypertension who were initiated on the agents between 1998 and 2006 and who remained on that hypertensive treatment as monotherapy for the duration of their time in the database. Anonymised patient data were drawn from the UK THIN general practice database. Hypertension was defined as a systolic blood pressure (SBP) reading ≥140 mmHg or diastolic BP (DBP) ≥90 mmHg. RESULTS: In a population means analysis, at 1 year, mean SBP reductions for patients receiving ARB therapy reached 13.2 mmHg compared to 11.1 mmHg for patients receiving ACE Inhibitors. For DBP mean reductions for patients receiving an ARB reached 7.8 mmHg compared to 6.7 mmHg for patients receiving an ACE Inhibitor. At 2 years, patients' mean SBP reductions reached 13.6 mmHg for the ARBs group and 11.2 mmHg for the ACE Inhibitors group. Similar results were also observed with DBP at 2 years with patients receiving ARB treatment reaching reductions of 8.3 mmHg compared to 7.1 mmHg reached by patients receiving an ACE Inhibitor. The comparisons were statistically significant (p<0.001) in a linear mixed multivariate analysis adjusting for repeated measures and random practice effects conditioning on baseline blood pressure, age, diabetes status, hypertensive diagnosis status and number of other non-hypertensive cardiovascular treatments. CONCLUSIONS: In a real-world setting, patients receiving ARBs as monotherapy are observed to achieve greater reductions in blood pressure compared to those receiving ACE Inhibitors as monotherapy.