Introduction: Patient safety and medication errors have received great attention and interest from health institutions. Drug return is a reverse logistics process that requires further analysis, because the delay or failure to return medications can create an accumulation of drugs in nursing units, favoring deviations and medication errors. The automated dispensing cabinets are a technological innovation that aims to reduce drug-related errors. The present study made an analysis of the amount of returned medications before and after the implantation of automated dispensing cabinets in a university hospital. Methods: This descriptive study presents a retrospective analysis of data on drug return collected from hospital reports published from 2013 to 2016. Results: Before the implantation of automated dispensing cabinets, the mean percentage of returned medications was 27%. In the first year after the implantation of automated dispensing cabinets, the mean percentage of returned medications was reduced to 4%. Conclusion: The implementation of the automated dispensing cabinets led to a reduction in drug return and in its associated risks, generating a positive impact on patient safety.