This book aims to providing the scientists and students with a guide for coral disease identification in the northern Red Sea, Egypt and to quantify the coral diseases relative to both biological and non biological stresses in the area. A data base on coral diseases in the area will be established, this will help using coral diseases as biomonitors of environmental impacts, in turn acting to remove or minimize these impacts. Removing or minimizing these impacts will improve the coral reef environment, in turn help to improving fish stocks, tourist attraction, national income; economic, scientific and medical values of coral reef ecosystems. However conserving the marine biodiversity will be improved.