A rapid and complete recanalization of the occluded artery is the ideal goal when intravenous (IV) recombinant tissue plasminogen activator (rt-PA) is administrated to patients with acute ischemic stroke, i.e., limiting the ongoing ischemia to achieve a better outcome. We explored the effect of complete versus partial recanalization of the occluded intracranial artery after IV thrombolysis on the infarct growth and evaluated the functional impact. Using diffusion-weighted (DWI) volumetric measurements before rt-PA administration (DWI(1)) and 24 h later (DWI(2)), we calculated the infarct growth in 36 consecutive patients with ischemic stroke treated with IV rt-PA, with the formula DWI(2)/DWI(1). Recanalization of the affected artery was assessed by transcranial Doppler (TCD) and magnetic resonance angiography (MRA) within 24 h of stroke onset. Three patients were eliminated from the analysis; 33 patients were fully analyzed (men: n = 23; mean (SD) age: 72.4 ± 16 years; time from stroke onset to rt-PA: 179 ± 54 min; mean NIHSS score at admission: 17). Patients achieving full recanalization by TCD had a smaller infarct growth, compared to those who had a partial or persistent occlusion after thrombolysis: 1.86 versus 2.91 (P = 0.017). This difference was not significant using MRA criteria: 2.01 versus 2.69 (P = 0.193). In the regression analysis, complete recanalization by TCD was an independent predictor of infarct growth (P = 0.045). Thus, complete recanalization measured by TCD within 24 h of IV thrombolysis was independently associated with smaller infarct growth.