Transient erythrocytosis during the neonatal period may result in serious complications. Among the well recognized problems are respiratory distress, acute heart failure, and death. Little attention has been ascribed to the neurologic complications of a high hematocrit level in the neonatal period. This report describes four pediatric patients with neurologic deficits presumably due to transiently high hematocrit levels during the neonatal period. The neurologic findings in these patients were consistent with the general diagnosis of cerebral palsy. We hypothesize that they may be representative of a group of patients with seizures, structural central nervous system defects, and/or mental retardation secondary to transient erythrocytosis. Moreover, prompt recognition and treatment of this hematologic finding may prevent the immediate or late appearance of such neurologic findings.