In support of Meaningful Use public health reporting, health departments are expanding their capacity to receive electronic health data. The Illinois Department of Health is working with the Illinois Health Information Exchange to build services and applications to improve the quality and utility of surveillance data. The Master Patient Index is an innovative component of the technology that will integrate public health data across surveillance systems. This presentation will cover the application of the MPI to ambulatory syndromic surveillance as well as other surveillance systems and highlight potential use cases.