Understanding causes of wrong-patient order entry (WPOE) can help develop interventions to reduce those medication errors. This review summarizes how organizations and providers identify WPOE, what data are being captured, and causes. The most common organizational detection method is the retract-and-reorder method whereby a medication order is cancelled then reordered on a different patient within a specified period of time. There was minimal data on how providers detect their own WPOE errors. Technology and physician workload were identified as contributors to WPOE.