Infectious bursal disease (also known as Gumboro disease) is a highly contagious viral disease caused by a small, hardy Avibirnavirus belonging to the family Birnaviridae which causes significant economic losses due to mortality, reduced performance and immuno-supression that lead to increased susceptibility to other diseases. The virus is resistant to a wide range of temperature and pH, although can be removed by most disinfectants. It is rapidly spread by direct contact between birds and can survi-ve for extended periods of time on inanimate objects, contaminated feed, etc. Currently, the disease has a worldwide prevalence and therefore it is not completely controlled. It is essential to know its main features to minimise the great economic impact which repre-sents for poultry farming. Thus, as veterinary surgeons have to face with this condition in their daily work, this hand-book performs a thorough review where the authors, highly qualified and experienced in dealing with this disease, supply visual resources (images, tables, flowcharts, etc.) accompanied by short pieces of text to describe the topic in an understandable and simple way. Therefore, the information included in this handbook helps the veterinarians to get overview of the topic so as to tackle it successfully day after day.