Cerebral vascular disease in children with sickle cell disease is characterized by progressive stenosis of large arteries of the skull base, which can be detected sensitively, specifically and unexpensively by transcranial Doppler. Because sickle cell disease is responsible for basal high velocities, criteria used for diagnosis of stenosis are different than those used in non sickled children and moreover in adults. Mean velocity higher than 2 meters per second is predictive of a 40% risk for stroke in the three following years, but transfusion program maintaining hemoglobin S under 30%, reduces the risk to 2%. It is important to test each child with sickle cell disease by the age of one or two years, in order to detect cerebral vasculopathy before overt stroke and its residual deficits and to initiate appropriate treatment