The 2014 National Action Plan for Adverse Drug Event Prevention has recognized adverse drug events (ADEs) as a national priority in order to facilitate a nationwide reduction in patient harms from these events. Throughout this effort, it will be integral to identify populations that may be at particular risk in order to improve care for these patients. We have undertaken a systematic review to evaluate the evidence regarding racial or ethnic disparities in ADEs with particular emphasis on anticoagulants, diabetes agents, and opioids due to the clinical significance and preventability of ADEs associated with these medication classes. From an initial search yielding 3302 studies, we identified 40 eligible studies. Twenty-seven of these included studies demonstrated the presence of a racial or ethnic disparity. There was no consistent evidence for racial or ethnic disparities in the eight studies of ADEs in general. Asians were most frequently determined to be at higher risk of anticoagulant-related ADEs, and black patients were most frequently determined to be at higher risk for diabetes agents-related ADEs. Whites were most frequently identified as at increased risk for opioid-related ADEs. However, few of these studies were specifically designed to evaluate racial or ethnic disparities, lacking a standardized approach to racial/ethnic categorization as well as control for potential confounders. We suggest the need for targeted interventions to reduce ADEs in populations that may be at increased risk, and we suggest strategies for future research.