We sought to determine whether early (< 8 hours) or delayed (8 to 24 hours) recanalization after stroke may be an independent variable in the improvement of clinical outcome in patients with occlusion of the middle cerebral artery. We prospectively studied 77 patients by combined Scandinavian Stroke Scale score at admission, repeated computed tomography and angiography before and after thrombolytic treatment at < 8 hours after stroke onset, and transcranial Doppler ultrasound 24 hours later. We tested an association between clinical and neuroradiological baseline characteristics, recanalization, and outcome as assessed by the modified Rankin Scale 4 weeks after stroke and determined the effect of recanalization on mortality and good outcome (Rankin Scale grades 0 to 3) by multiple logistic regression analyses. Recanalization rates at 8 and 24 hours after stroke correlated with sites of occlusion (middle cerebral artery branch, 73% and 73%, trunk, 27% and 38%, respectively; intracranial internal carotid artery bifurcation, 14% and 14%; P = .002), collaterals (good, 43% and 51%, respectively; scarce, 17% and 19%, respectively; P = .01), and Scandinavian Stroke Scale score at admission (P = .002). Six of 6 patients with delayed recanalization had good outcomes. Recanalization at < 8 hours after symptom onset had no independent predictive value for good outcome (P = .69). Recanalization at 24 hours increased the proportion of good outcomes from 23% to 75% in a subgroup of patients. Recanalization did not independently affect mortality (P > .15). Even if delayed, arterial recanalization may improve clinical outcome in a subgroup of patients with middle cerebral artery occlusion.