We studied the effect of transcranial 2MHz Doppler ultrasound (US) on the recanalization and outcome of stroke patients suffering from acute middle cerebral artery occlusion. All patients underwent intravenous recombinant tissue-type plasminogen activator thrombolysis. Eleven patients were randomly selected for continuous US monitoring (C-US) over 1 hour; 14 patients were selected for the control group. The C-US group showed a higher grade of recanalization after 1 hour but also a higher number of intraparenchymal bleedings. Overall, a favorable functional outcome occurred more frequently in the C-US group (Barthel index, p = 0.037) after 3 months.