Cerebrovascular accidents occurred in three children with homozygous sickle cell anemia. The first case was that of a young girl with three carotid aneurysms who developed a meningeal hemorrhage. Angiography in the second child, who had had recurrent hemiplegias, showed multiple stenoses of the cerebral arteries, with a moya-moya appearance. The third case was a boy with hemiplegia and signs of a lesion in the sylvian region on computed brain tomography. The outcome was favorable in cases 1 and 3, but there were marked sequelae in the second case. Published reports indicate a different frequency for these accidents in the USA (17 to 26 p. cent) and black Africa (less than 5 p. cent). The mechanism of these accidents is discussed. The presence of multiple aneurysms may be only coincidental, but they could result from the very widespread arterial lesions observed in sickle cell anemia. The moya-moya disease in this case is related to the fibromuscular dysplasia of the cerebral arteries occurring during homozygous sickle cell anemia. It is reported fairly frequently in the published literature and appears to run a more severe course than non-drepanocytic moya-moya cases, with many deaths and marked neurological sequelae. Care is required when conducting cerebral arteriography in order to detect these lesions in cases of homozygous sickle cell anemia, especially when computed brain tomography is not possible or does not supply confirmation. Exchange transfusion can prepare these patients for arteriography by reducing hemoglobins levels to 20 p. cent, and it is apparently also a useful adjuvant during therapy of these accidents.