Irbesartan is an angiotensin II subtype 1 (AT1) receptor blocker (ARB) that inhibits the actions of angiotensin II on the renin-angiotensin-aldosterone system. Once-daily administration of irbesartan provides 24-hour control of blood pressure in hypertensive patients. A renoprotective effect of irbesartan in hypertensive patients with type 2 diabetes at both the early and later stages of diabetic nephropathy has been demonstrated in two large, randomized, double-blind, placebo-controlled, multinational trials: the Irbesartan Microalbuminuria Type 2 Diabetes in Hypertensive Patients (IRMA 2) trial and the Irbesartan Diabetic Nephropathy Trial (IDNT). In addition to the angiotensin II antagonistic activity, irbesartan shows partial PPARγ agonistic activity and is highly distributed to the kidney, the heart and white adipose tissue. Indeed, ARBs which have partial PPARγ agonistic activity such as irbesartan and termisartan have been reported to improve insulin resistance and lipid profiles in diabetes mellitus patients as well as metabolic syndrome patients. Thus, a class of ARB which has partial PPARγ agonistic activity might be termed as “metabosartan”. Beneficial therapeutic efficacy of irbesartan in hypertensive patients might result from substantial dual AT1 receptor antagonist/ PPARγ agonist actions and relatively high concentration in end-target tissues. Here, we summarized the potential therapeutic values of irbesartan.