The introduction of immunoassay technology in the early 1970s laid the foundation for the development of diagnostic procedures that continue to this day, both in routine laboratories and in research. With the increasing automation of workflows in the 1990s, which experienced a significant boost primarily through intelligent software control, the previously manually performed immunoassays are increasingly being automated. This is done either in open systems, which can process reagent kits from various manufacturers, or in closed systems that are only compatible with reagents from the respective instrument manufacturer. Automation in the clinical laboratory has led to a steady increase in the number of tests performed in recent years. The advantages of laboratory automation affect both the pre-analytics, with its sometimes complex manual steps, as well as the analytics itself, and the post-analytical processing of data. This chapter describes the technical challenges and the transfer of immunoassays to automated systems.