OBJECTIVES: To analyze the percentage of patients treated with anti-hypertensive medication in mono or dual therapy that experienced a CV event. METHODS: A retrospective study of the Southwestern Ontario database which contains chart-abstracted information from primary health care facilities in Ontario, Canada was performed.  Patients with hypertension were identified as those with a recorded Blood Pressure (BP) exceeding 140/90 mmHg, chart entry of a diagnosis of hypertension, or use of anti-hypertensive medication. Patients treated either in mono or dual therapy with angiotensin II receptor blockers (ARBs), ACE Inhibitors (ACEIs) and Calcium Channel Blockers (CCBs) were included.  The number of patients who experienced at least one CV event from 2003 to 2008 was recorded. CV events are stroke, myocardial infarction, congestive heart failure, peripheral vascular disease, coronary heart disease, atrial fibrillation or transient cerebral ischemic attack.  Due to the well known comparable safety profile of the compounds, a safety analysis was not performed. RESULTS: A total of 53,064 patients treated with an ARB, ACEI or CCB in mono or dual therapy were identified.  The proportions of treated patients who experienced a CV event were 4.3% on ARBs compared to 7.0% on ACEIs and 11.0% on CCBs. These differences were statistically significant (p<0.001).  Within the ARB class, the proportions of treated patients who experienced a CV event were 3.0% on irbesartan compared to 4.6% on losartan, 5.0% on valsartan and 5.0% on candesartan.  These differences were statistically significant (p<0.02). CONCLUSIONS:   In patients treated in mono or dual therapy, those treated with an ARB experienced significantly fewer CV events than those treated with an ACEI or a CCB.  Amongst the ARB-treated patients, those treated with irbesartan as part of their therapy experienced significantly less CV events than those treated with another ARB.