Multi-agent systems are one of the most exciting research areas in Artificial Intelligence. In the last ten years there has been a growing interest in the application of agent-based systems in health care. Moreover, a growing European community of researchers interested in the application of intelligent agents in health care emerged as a result of the activities within the AgentCities.NET European network and the AgentLink III Technical Forum Group on Healthcare Applications of Intelligent Agents. This book reports on the results achieved in this area, discusses the benefits (and drawbacks) that agent-based systems may bring to medical domains and society, and also provides a list of the research topics that should be tackled in the near future to make the deployment of health-care agent-based systems a reality.