One challenge when implementing case-based learning, and other approaches to contextualized learning, is determining which clinical problems to include. This article illustrates how health care utilization data, readily available from the National Center for Health Statistics (NCHS), can be incorporated into an educational needs assessment to identify medical problems physicians are likely to encounter in clinical practice. The NCHS survey data summarize patient demographics, diagnoses, and interventions for tens of thousands of patients seen in various settings, including emergency departments (EDs), clinics, and hospitals.Selected data from the National Hospital Ambulatory Medical Care Survey: Emergency Department illustrate how instructional materials can be derived from the results of such public-use health care data. Using fever as the reason for visit to the ED, the patient management path is depicted in the form of a case drill-down by exploring the most common diagnoses, blood tests, diagnostic studies, procedures, and medications associated with fever.Although these types of data are quite useful, they should not serve as the sole basis for determining which instructional cases to include. Additional sources of information should be considered to ensure the inclusion of cases that represent infrequent but high-impact problems and those that illustrate fundamental principles that generalize to other cases.