Immunization registries have been promoted as a critical tool that can encourage increased vaccination coverage. The benefits of an immunization registry (also known as an Immunization Information System, IIS) are believed to be so substantial that the Centers for Disease Control and Prevention established a national objective to have at least 95% of US children, age 6 years or younger and that have two or more vaccinations, to be included in a fully operational population-based immunization registry. This project aimed to compare the deduplication rate and accuracy of demographic record duplication processes implementation by Oregon Immunization Alert's current and new deduplication systems.