Objective To determine the frequency of acute care visits and risk factors for central nervous system (CNS) events in children with homozygous sickle cell disease (SCD-SS) with an acute headache. Study design This is a retrospective cohort study of acute care visits for headache in children with SCD-SS. The prevalence of headache visits, neuroimaging evaluation, and acute CNS events were calculated and clinical and laboratory variables assessed. Results Headache was the chief complaint in 102 of 2685 acute care visits (3.8%) by children with SCD-SS. Acute CNS events were detected in 6.9% of these visits. Neuroimaging was performed in 42.2% of visits, and acute CNS events were identified in 16.3% of studies. Factors associated with acute CNS events included older age, history of stroke, transient ischemic attack, or seizure, neurologic symptoms, focal neurologic exam findings, and elevated platelets. Conclusions Acute headache is common in pediatric SCD-SS and more frequently associated with acute CNS events than in the general pediatric population. A history of stroke, transient ischemic attack, seizures, neurologic symptoms, focal neurologic exam, or elevated platelet counts at presentation warrant confirmatory imaging studies. Whether a more limited workup is adequate for other children should be confirmed in a larger, prospective study. (J Pediatr 2011;159:472-8).