BACKGROUND:Posterior reversible encephalopathy syndrome may occur frequently and be underrecognized in children and young adults admitted to a pediatric critical care unit. METHODS:Patients <21 years of age with the diagnosis of posterior reversible encephalopathy syndrome were reviewed in this retrospective cohort study conducted over a 30-month period. RESULTS:There were 2588 admissions to pediatric critical care unit, 226 neurology service consultations, and 10 patients diagnosed with posterior reversible encephalopathy syndrome (incidence of 1 in 259 pediatric critical care unit admissions, 0.4%). The majority of posterior reversible encephalopathy syndrome patients (9/10) presented with generalized tonic and or clonic seizures. Apart from hypertension and cytotoxic medication use, anemia, a previously unreported risk factor, was found in all 10 (100%) patients with posterior reversible encephalopathy syndrome. One-year follow up available in eight patients showed no residual neurological deficits attributable to posterior reversible encephalopathy syndrome with significant resolution of white matter signal abnormalities on neuroimaging. CONCLUSION:Our case cohort includes an estimation of incidence of posterior reversible encephalopathy syndrome in children and young adults with 1-year follow-up and anemia as a potential previously unreported risk factor.