Medication errors are thought to be common in neonatal intensive care units (NICUs). This study compared the incidence of medication errors occurring in two NICUs over a three-month period. Over the study period, there were an average of 3.38 medication errors per patient and three-quarters of neonates experienced at least one error. Preterm neonates experienced medication errors significantly more often than term neonates. Errors in prescription dosage and administration were the most common errors.