Transcranial Doppler (TCD) is an effective method for screening patients with sickle cell disease (SCD) at risk for first stroke. Its usefulness in monitoring children with SCD receiving transfusions has not been established. The authors studied 17 children with SCD evaluated with TCDs and magnetic resonance angiograms (MRAs) while receiving transfusion therapy. Patients with normalized TCDs had normal MRAs that remained normal on transfusions. Patients with persistently abnormal TCDs had abnormal MRAs. In these children, TCD velocities decreased but rarely reverted to normal. Patients with low TCD velocities (<70 cm/s) had corresponding vasculopathy on MRA. Low velocities may be a risk factor for stroke and should be followed. Overall, there was good correlation between TCD velocity changes and MRA analysis.