Existing data on the use of computerized provider order entry (CPOE) in the ambulatory care setting is limited, consisting mainly of studies of home-grown systems or settings where CPOE usage was mandatory. Although some of these studies have shown that CPOE can reduce medication errors, this study of the implementation of a commercial CPOE system in academic clinics found no reduction in prescribing errors, probably because the vast majority of clinicians continued handwriting prescriptions. The results of this study likely reflect issues that arise when implementing new technologies outside of a research setting.