© 2017, Health and Medical Publishing Group. All rights reserved. Background. Paediatric patients are particularly prone to medication errors as they are classified as the most fragile population in a hospital setting. Paediatric medication errors in the South African healthcare setting are comparatively understudied. Objectives. To determine the incidence of medication errors in neonatal and paediatric inpatients, investigate the origin of medication errors that occurred and describe and categorise the types of medication errors made in both the neonatal intensive care unit (NICU) and paediatric wards. Methods. The study followed a prospective, quantitative design with a descriptive approach. A prospective record review of inpatients’ medication charts was undertaken to determine what was prescribed by the physician, dispensed by the pharmacy and administered by the nurses. The researcher also directly observed the preparation and administration techniques as performed by the nurses. A medication error checklist was used to collect the data. Results. A total of 663 medication errors were detected in 227 patients over the study period of 16 weeks, of which 177 (78%) patients had one or more error(s). There were 338 (51%) administration errors and 309 (47%) prescribing errors. Incorrect dosing was the most frequent type of error (34%), followed by omission of medication (18.5%) and medication given at the incorrect time (12%). The causes of these medication errors were mostly due to miscalculation (26%), failure to monitor (15%) and procedures not followed (15%). Anti-infectives (43%) and analgesics (25%) had the most errors. In 118 (67%) patients the errors resulted in no harm to the patient, whereas in 59 (33%) patients the medication error resulted in some level of harm. Conclusion. The incidence of medication errors in the NICU and paediatric wards at the teaching hospital was higher than values reported elsewhere globally. Most errors occur during prescribing and administration of medication. Dosing errors are a common problem in paediatrics. Therefore, a formalised system to record these errors should be introduced alongside regular discussions on preventive measures among the multidisciplinary team.