Although programs such as the National High Blood Pressure Education Project emphasize that all patients with hypertension should be treated, it is perhaps natural for physicians to question the usefulness of aggressively treating those patients who have modestly elevated blood pressure levels but are otherwise healthy, asymptomatic individuals. Using the example of stroke, this review summarizes the clinical trial data demonstrating the efficacy of antihypertensive therapy in patients with severe and nonsevere forms of hypertension. Suggestions are made that will help practitioners to apply results from the published literature in clinical practice. The evidence suggests that treating patients with nonsevere hypertension would prevent a larger proportion of the population-wide burden of stroke than treating only those with more severe hypertension. Helping physicians to understand and apply this evidence will bring us closer to the goal of population-wide treatment and control of high blood pressure.