Aliskiren is the first orally active inhibitor of renin to be approved for clinical use as an antihypertensive agent. The development program has established that at the licensed doses of 150 mg and 300 mg, there are dose-related falls in blood pressure comparable to those seen with other major classes of antihypertensive drugs and that these falls are associated with a placebo level of side effects. Aliskiren was found to be effective either as monotherapy or in combination with drugs from the other major classes. As expected, there was a greater benefit from adding aliskiren to natriuretic drugs than to other blockers of the renin system. However, there was also some consistent benefit from dual renin blockade. Aliskiren is likely to be of most value in patients uncontrolled by, or intolerant of, other classes. Rational understanding of the renin system will maximize its value, for instance, by encouraging greater use of natriuretic agents in patients with resistant hypertension to render their hypertension renin dependent. Whether there are cardiovascular benefits other than blood pressure control in blocking the renin system remains to be demonstrated. It is hoped that long-term outcome studies with aliskiren will finally allow this question to be answered.