Forty-three children and adolescents (8-16 years old) with sickle cell disease (SCD) and no overt neurologic dysfunction were evaluated with the Wechsler Intelligence Scale for Children-Revised (WISC-R), the Wide Range Achievement Test (WRAT), and an age-appropriate version of the Luria-Nebraska Neuropsychological Battery (LNNB). Thirty similar-aged siblings were controls. WISC-R performance and full-scale IQs were lower (p less than 0.05) for patients than sibling controls. No significant differences were seen on the WRAT. Patients with SCD missed more school days than controls (p less than 0.001) but did not differ from controls in academic performance or the proportion in special education. On the LNNB, scores for patients and controls 13 years and older did not differ. However, young patients had significantly elevated (abnormal) scores compared with controls on the following scales: expressive speech, writing, reading, arithmetic, memory, and pathognomonic. The possibility that subtle neuropsychological deficits in younger patients with SCD reflect either subclinical strokes or a predisposition for strokes merits further investigation in a large multi-institution study.