Computerized physician order entry (CPOE) systems can create unintended consequences. These include medication errors and adverse drug events. We look at a less understood error; patient misidentification. First, two email surveys were used to establish potential risk factors for this error. Next, an automated detection trigger was designed and validated with inpatient medication orders at a large pediatric hospital. The incidence was 0.064% per medication ordered. Finally, a case-control study identified the following as significant risk factors on multivariate analysis: patient age, last name spelling, bed proximity, medical service, time/date of order, and ordering intensity. These results can be used to improve patient safety by increasing awareness of high risk situations and guiding future research.