Objectives. This multicenter, three-armed, open-labeled study investigated patient compliance of patients receiving irbesartan, angiotensin-converting enzyme (ACE) inhibitors or calcium-channel blockers (CCB) for essential hypertension for a 6-month period. Patients were either newly diagnosed or switched from existing antiltypertensive medication due to lack of efficacy or side-effects. Methods. Patients were started monotherapy with irbesartan (n=377), ACE inhibitors (n=298) or CCB (n=308) and were reevaluated on 1st, 3rd, and 6th months of the treatment. The primary endpoint was patient compliance, assessed by proportion of patients who had taken their study medication every day. Efficacy was recorded as mean reductions in blood pressure and the proportion of patients whose blood pressure normalized. Tolerability was assessed by reported adverse events. Results. Significantly more patients receiving irbesartan had complied with study medication after 3 and 6 months of treatment than ACE inhibitors or CCB. Significantly fewer patients receiving irbesartan needed to change their antihypertensive medication. All three study treatments exhibited similar efficacy profiles, but irbesartan had significantly less adverse events. Conclusions. This study demonstrated that patient compliance to irbesartan was significantly superior to other study treatments. Irbesartan is therefore a suitable first-line therapy for essential hypertension in everyday clinical practice.