This book allows readers to gain an in-depth understanding of the role of real-world data in pharmacoepidemiology, and highlights the strengths and limitations of the respective databases with regard to pharmacoepidemiological research. Over the past decade, the increasing use of real-world data in pharmacoepidemiological research has been accompanied by a growing recognition of the value of real-world evidence in clinical and regulatory decision-making. Electronic healthcare databases allow analyses of drug and vaccine utilization in routine care after approval, as well as investigations of their comparative effectiveness and safety. They are especially useful for the identification of rare risks and rare drug exposures over long periods of time, and as such sustainably extend the basis for drug safety research.  This book provides an introduction to the role of real-world data in pharmacoepidemiological research and the main developments in the last 15years. It also offers a comprehensive overview of the general classification characteristics of databases, together with their strengths and limitations, and a detailed description of 21 individual databases, written by professionals who work with or maintain them.