The use of computerized provider order entry (CPOE) systems, in which clinicians place orders for tests, labs, and medications electronically, has grown rapidly in both inpatient and outpatient settings. Although research has shown that implementation of CPOE can reduce prescribing errors in both inpatient and outpatient settings, additional studies have found that errors continue to occur. In this systematic review, researchers identified multiple factors linked to CPOE prescribing errors, including flaws in functional design and underlying clinical decision support systems, as well as insufficient system flexibility leading to user workarounds. The authors suggest that further consideration must be given to human factors design principles. A recent Annual Perspective highlighted some of the ongoing challenges associated with CPOE.