It is unclear whether antihypertensive treatment before stroke affects acute ischemic stroke severity and outcome. To evaluate this association, the authors studied 482 consecutive patients (age 78.8±6.7 years) admitted with acute ischemic stroke. Stroke severity was assessed at admission with the National Institutes of Health Stroke Scale (NIHSS). The outcome was assessed with rates of adverse outcome (modified Rankin scale at discharge ≥2). Independent predictors of severe stroke (NIHSS ≥16) were female sex and atrial fibrillation. Treatment with diuretics before stroke was associated with nonsevere stroke. At discharge, patients with adverse outcome were less likely to be treated before stroke with β-blockers or with diuretics. Independent predictors of adverse outcome were older age, higher NIHSS at admission, and history of ischemic stroke. Treatment with diuretics before stroke appears to be associated with less severe neurologic deficit in patients with acute ischemic stroke.