Of 44 children with hemolytic-uremic syndrome seen at Milwaukee Children's Hospital, 15 (34%) had neurological involvement. This group contained 8 boys and 7 girls, with a mean age of 3 1/4 years. Twelve patients had seizure within 48 hours of admission. Seizures were associated with hypertension, fever, hyponatremia, or hypocalcemia. Other neurological symptoms included altered consciousness, behavioral changes, diplopia, and dizziness. Hemiparesis (4 patients), eye involvement (7 patients), decerebrate posturing (2 patients), and ataxia (1 patient) were present on physical examination. Cerebrospinal fluid examination showed increased protein in 4 of 11 patients. Electroencephalograms were abnormal in all 9 patients tested. Computed tomographic and radionuclide scans showed evidence of vascular abnormalities in 4 of the 14 patients studied. Complete neurological recovery occurred in only 6 of the 15 children, while the remaining 6 demonstrated residual hemiparesis, seizures, and cortical visual defect. In those children with neurological involvement, there was a higher incidence of residual hypertension (49% versus 11%), chronic renal damage (40% versus 3.5%), and death (28% versus 0%), suggesting that central nervous system involvement indicates severe hemolytic-uremic syndrome.