Transient elevation of arterial blood pressure (BP) is frequent in acute ischemic stroke and may help to increase perfusion of tissue jeopardized by ischemia. If this is true, recanalization may eliminate the need for this BP elevation. We analyzed BP in 149 patients with acute ischemic stroke on admission to the hospital and 1 and 12 hours after intraarterial thrombolysis. BP values of patients with adequate recanalization were compared with BP values of patients with inadequate recanalization. Recanalization was determined on cerebral arteriography after thrombolysis using thrombolysis in myocardial infarction grades. Systolic, mean, and diastolic arterial BP decreased significantly from admission to 12 hours after thrombolysis in all patients (P<0.001). Before thrombolysis, patients with adequate and inadequate recanalization showed equal systolic (147.4 and 148.0 mm Hg), mean (102.1 and 104.1 mm Hg), and diastolic (79.5 and 82.1 mm Hg) BP values. Twelve hours after thrombolysis, patients with adequate recanalization had lower values than those with inadequate recanalization (systolic BP, 130 versus 139.9 mm Hg; mean BP, 86.8 versus 92.2 mm Hg; and diastolic, BP 65.2 versus 68.3 mm Hg). Two-way repeated ANOVA analysis showed a significant group x time interaction for systolic BP, indicating a larger systolic BP decrease when recanalization succeeded (P=0.019). The course of elevated systolic but not diastolic BP after acute ischemic stroke was found to be inversely associated with the degree of vessel recanalization. When recanalization failed, systolic BP remained elevated longer than when it succeeded.