Aliskiren is the first known representative of a new class of non-peptide orally active renin inhibitors that blocks the renin-angiotensin-aldosterone-system (RAAS) at its rate-limiting step. It induces a net reduction in plasma renin activity (PRA), angiotensin II and aldosterone levels. Aliskiren is effective in reducing blood pressure (BP) and is well tolerated. The incidence of adverse events and the number of study discontinuations as a result of adverse events during aliskiren treatment were relatively low and generally not dissimilar from placebo. In placebo-controlled studies, aliskiren showed a dose-related systolic/diastolic BP lowering effect at doses between 75 and 300 mg/day. When compared to active treatments, aliskiren was generally as effective as hydrochlorothiazide, angiotensin-converting-enzyme (ACE) inhibitors, angiotensin receptor blockers (ARBs) and beta-blockers, in reducing BP. Aliskiren exhibits synergistic effects when combined with drugs that lead to a reactive increase in the PRA, such as diuretics, ACE inhibitors or ARBs. Although in clinical studies aliskiren proved to reduce proteinuria, the early termination of the Aliskiren Trial in Type 2 Diabetes Using Cardiovascular and Renal Disease Endpoints (ALTITUDE) confirms previous concerns about the full suppression of the RAAS, in this case with aliskiren combined with ACE-inhibitors or ARBs, in patients with diabetes and concomitant renal impairment. This review summarizes the available data on its safety profile and its clinical development for treatment of arterial hypertension, diabetes and nephropathy.