Irbesartan (SR 47436; BMS-186295) is a selective non-peptide antagonist of angiotensin II type 1 receptor (AT1). Irbesartan inhibits the action of angiotensin II, which acts through the binding to the AT1 receptor. Many experimental and clinical data show that activation of AT1 receptors plays the crucial role in the development of hypertension, hypertrophy of left ventricle, progression of lipid disorders and impairment of renal function. Therefore, the pharmacological intervention with angiotensin II type 1 receptor antagonists could be used as a new therapeutic option in treatment of hypertension and its complications. The advantage of irbesartan is its long lasting blood pressure lowering action and the possibility of taking it once a day. The principle of its action is not only limited to blocking the AT1 receptor, but it also participates in many other reactions of the renin-angiotensin-aldosterone system. According to the reports published, irbesartan and other antagonists of angiotensin II type 1 receptor seem to be a promising complement in the treatment of idiopathic hypertension, especially in patients with heart failure, diabetes and impaired renal function. Several studies showed that in addition to its long blood pressure lowering action (study of Pool, Fogari, Stumlple, Minran)--(possibility of taking the drug once a day), the AT1 antagonists reduced proteinuria (Sica et al.) without decreasing the creatinine clearance, improved the function of endothelium and inhibited the mitogen and proliferative action of angiotensin II on cardio-vascular system (Kahan et al., Tonkon et al., SILVER and ELITE trail).