Wrong-patient errors have long been a risk in hospitals. In one seminal case, a patient underwent an invasive procedure intended for another patient with a similar name. In the era of electronic medical records, errors such as entering notes or ordering medications for the wrong patient may occur as a consequence of multitasking. This AHRQ-funded study evaluated the effectiveness of an alert system, which required entry of an appropriate clinical diagnosis, at preventing wrong-patient medication errors in a computerized provider order entry system. Although the system did correctly identify and prevent incorrect prescriptions, 4000 alerts were required to prevent a single error. Other studies have successfully used forcing functions, or simply placing the patient's photograph on the order screen, to prevent wrong-patient errors.