The Authors critically review the problem of Hodgkin's disease (HD) in the light of the most recent findings obtained by means of immunohistochemistry and molecular biology. The following topics are discussed in details: 1) the definition of the borders between HD and non-Hodgkin's lymphomas, 2) the histogenesis of Hodgkin's and Reed-Sternberg cells, 3) the relationships between neoplastic cells and microenvironment, and 4) the pathogenetic role of Epstein-Barr virus in the onset of HD.