The bursa of Fabricius has a history and a future. The history included its description by Hieronymus Fabricius and the discovery in the 1950s of its pivotal role in humoral immunity. The apparent obligate role of the bursa in B-cell development was modified by research in the 1960s and 1970s which described the synthesis of immunoglobulin in bursaless birds and led to the concept of extra bursal sites. Then in the 1980s, supported by the research of the past 25 years and the new technology, the obligate role of the bursa in orchestrating the V-gene repertoire-antibody diversity was revealed. Microenvironmental studies in the 1970s and 1980s announced the importance of bursal epithelium, secretory dendritic cells, and other reticuloepithelial cells in interpreting the ontogeny of B-cell differentiation. The past history of the bursa will be remembered for its contribution to present and future research and the present and future will be promising if the experiences of the past are not forgotten.