The risk of stroke is strongly and persistently related to the usual level of both systolic blood pressure (SBP) and diastolic blood pressure (DBP). This relation holds for primary and secondary stroke, both ischemic and hemorrhagic. The Perindopril Protection Against Recurrent Stroke Study (PROGRESS) has now provided definitive evidence that lowering the blood pressure of patients with preexisting cerebrovascular disease (prior stroke or transient ischemic attack [TIA]) also reduces the incidence of secondary stroke. PROGRESS showed that a flexible blood pressure-lowering regimen involving an angiotensin-converting enzyme inhibitor (perindopril) and a diuretic (indapamide) reduces the incidence of stroke, major coronary events, and major vascular events by 28%, 26%, and 26%, respectively. These benefits were associated with an average reduction of 9.0 mm Hg (SBP) and 4.0 mm Hg (DBP). The 28% reduction in stroke incidence translated into a 24% reduction in ischemic stroke and a 50% reduction in hemorrhagic stroke. Combination therapy with perindopril and indapamide decreased blood pressure more effectively than did perindopril monotherapy (mean reduction of 12.3 mm Hg [SBP] and 5.0 mm Hg [DBP] vs 4.9 mm Hg [SBP] and 2.8 mm Hg [DBP], respectively) and was equally effective in reducing stroke risk in patients with and without hypertension. In conclusion, blood pressure-lowering therapy is now established as the most important measure for primary and secondary stroke prevention. Results of PROGRESS suggest that antihypertensive treatment with a combination of perindopril plus indapamide should now be routinely considered for all patients with previous stroke or TIA.