The increasing reliance on electronic health data has created new opportunities for the secondary use of clinical data to impact practice. We analyzed the secondary uses of clinical data at the University of Washington (UW) to better understand the types of users and uses as well as the benefits and limitations of these electronic data. At the UW, a diverse population is utilizing different elements of clinical data to conduct a wide· variety of studies. Investigators are using clinical data to explore research questions, determine study feasibility and to reduce the burden of manual chart abstraction. Discovered limitations include difficult-to-use data formatting, researchers' lack of understanding about the data structure and organization resulting in mistrust, and difficulty generalizing data to fit needs of many specialized users.