This book constitutes the thoroughly refereed post-conference proceedings of the 4th International Conference, eHealth 2011, held in Málaga, Spain, in November 2011. The 20 revised full papers presented along with 8 short papers were carefully reviewed and selected from numerous submissions in total and cover a wide range of topics including social media analysis, knowledge integration and EPR, personalisation and patient support systems, early warning systems and mobile monitoring, games and learning, security, privacy and prevention, online support for professionals and patients, agents in eHealth, online communities of practice, eHealth solutions, social media surveillance, and communication and data integration.