Coral reefs are the most spectacular and diverse ecosystems in the marine environment. Over the last decades, however, dramatic declines of coral reef communities have been observed. Corals are endangered due to natural and anthropogenic detrimental factors, such as global warming and environmental pollution. Based on an international meeting on "Coral Health and Disease" in Eilat, Israel in April 2003, the book starts with case studies of reefs, e.g. the Red Sea, Caribbean, Japan, Indian Ocean and the Great Barrier Reef. The second part on microbial ecology and physiology describes the symbiotic relations of corals and microbes, and the microbial role in nutrition or bleaching resistance of corals. Particular coral diseases such as aspergillosis, white pox, black and white band diseases are treated in the third part. Finally, various hypotheses of the mechanisms of coral bleaching, including a projection of the future of coral reefs, are discussed.