Objective: to identify the risk factors in medication errors in a high-complexity chilean public hospital. Method: a research study with a quantitative approach; an exploratory, descriptive and cross-sectional study, with retrospective temporal cuts. The study population consisted of 50 reports of adverse events related with the medication administration process generated between 2014 and 2017 in the Medical and Surgery services of the Magallanes Clinical Hospital, Chile. The classification of the National Coordinating Council for Medication Error Reporting and Prevention was used for data collecting, performed during May and June 2018, and the data were analyzed by means of descriptive statistics. Results: among those involved in the medication errors, the following professions are predominant: nurses, 21 (42%); Medical and Surgery nursing technicians, 18 (36%), and nursing technicians working in the Pharmacy, 7 (14%). The most frequent medication errors were the following: medication transcription, 16 (32%); preparation, 13 (26%); and administration, 11 (22%). The following risk factors stand out in the notified cases: communication and interpretation problems, 13 (26%); incorrect interpretation of the prescription at dispensation, 7 (14%); factors associated with work organization such as insufficient compliance with the priority safety practices, 11 (22%), and individual factors, 9 (18%). Conclusion: more information is required about medication errors to identify the risk factors and to establish strategies for their prevention; consequently, the notification of adverse events must be promoted as a preventive measure.