Blood pressure (BP) is one of the most important and common vascular risk factors but it is often poorly controlled. Inhibition of the renin-angiotensin-aldosterone system (RAAS) provides beneficial effects in hypertensives. The association of low-dosed diuretics in combination with RAAS blocking agents allows maximum benefit from potassium depletion and control of compensatory increase in renin secretion, so increasing the efficacy and safety of RAAS blockers. Irbesartan is a potent and selective angiotensin II subtype 1 receptor antagonist indicated for use in patients with hypertension, including those with type 2 diabetes mellitus and nephropathy. Once-daily irbesartan administration provides 24h control of BP. In patients with mild-to-moderate hypertension, irbesartan was as effective as enalapril, atenolol and amlodipine, and more effective than losartan and valsartan in terms of absolute reduction in BP and response rate. Irbesartan also induced regression of left ventricular hypertrophy. Moreover, irbesartan 300 mg/day exerts a significant renoprotective effect in hypertensive type 2 diabetic patients. The relative risk of doubling of serum creatinine was significantly lower with irbesartan than amlodipine or placebo. Irbesartan was also effective in non-diabetic nephropatic patients. Moreover, irbesartan has peroxisome proliferator-activated receptor agonistic effects in in vitro studies, and it also demonstrated beneficial effects on inflammatory markers of atherosclerosis and endothelial function. The overall incidence of adverse events is similar to that of placebo. A fixed dose of hydrochlorothiazide (HCTZ) and irbesartan shows additive antihypertensive effect in a dose dependent manner up to HCTZ 25 mg and irbesartan 300 mg with high tolerability in diverse patient groups. Combination effects on end organ protection must be evaluated by broad spectrum studies. Ongoing trials about irbesartan and its combination with diuretics may provide necessary data to interpret the value of this association among others.