The prevalence and nature of medication errors and preventable adverse drug events in pediatric and neonatal intensive care units were examined in this systematic review. In the 35 quantitative studies included in the review, prescribing and medication administration errors were the most common errors reported, with dosing errors the most frequent subtype, in both types of critical care units. The authors concluded that critically ill children admitted to intensive care units frequently experience medication errors and identified important targets to guide remediation efforts.