Public health nurses (PHNs) play critical roles in public health surveillance systems in the United States. Increased understanding of public health surveillance systems can help PHNs appreciate their role in surveillance and improve the quality and usefulness of surveillance data. This paper describes the National Immunization Survey, the public health surveillance system currently in place for tracking immunizations, as well as immunization registries and HEDIS performance indicators, two emerging approaches to immunization surveillance. The contributions of public health nursing to these systems and implications for public health nursing practice are discussed. High quality public health surveillance information is essential for monitoring the progress of disease trends and program effectiveness. PHNs can help assure the quality of surveillance data.