Patients with severe acute chest syndrome (ACS) requiring endotracheal intubation and erythrocytopheresis are at increased risk for neurologic morbidity. This study examines patients with sickle cell disease who developed severe episodes of ACS, leading to endotracheal intubation, ventilatory support for respiratory failure, and erythrocytapheresis. Magnetic resonance imaging (MRI) and magnetic resonance angiography (MRA) studies, a neurologic examination by a pediatric neurologist, and cognitive testing were done in all patients. Five consecutive patients, aged 3 to 9 years, were identified with severe ACS. All patients developed neurologic complications resulting from ACS episodes, including seizures (n = 2), silent cerebral infarcts (n = 3), cerebral hemorrhage (n = 2), and reversible posterior leukoencephalopathy syndrome (n = 3). Children with severe ACS should have a magnetic resonance image of the brain, neurologic examination by a neurologist, and cognitive testing to detect the presence of neurologic morbidity.