Infectious bursal disease (IBD) (Gumboro disease) has been described throughout the world, and the socio-economic significance of the disease is considerable world-wide. Various forms of the disease have been described, but typing remains unclear, since antigenic and pathotypic criteria are used indiscriminately, and the true incidence of different types is difficult to determine. Moreover, the infection, when not fatal, leads to a degree of immunosuppression which is often difficult to measure. Finally, the control measures used are subject to variations, and seldom follow a specific or standardised plan. In the context of expanding international trade, the authors provide an overview of existing knowledge on the subject to enhance available information on the epidemiology of IBD, the identification of reliable viral markers for diagnosis, and the implementation of specific control measures to ensure a global and co-ordinated approach to the disease.