The Institute of Medicine’s Committee on Review of Priorities in the National Vaccine Plan has prepared a letter report entitled Initial Guidance for an Update of the National Vaccine Plan: A Letter Report to the National Vaccine Program Office, for the Department of Health and Human Services National Vaccine Program Office (NVPO). The report provides initial guidance, partly based on a review of the 1994 plan, on the development of the update to the National Vaccine Plan. The update is being coordinated by NVPO. Draft portions of the updated plan will form the subject of upcoming meetings of the IOM committee with invited national stakeholders. The letter report provides guidance on key process and content areas to be considered in developing the update.