The theoretical bases of Hodgkin's disease (HD) have recently been revised in the light of new findings obtained by means of immunohistochemistry and molecular analysis. These findings have questioned the concept that HD is a unique entity and have made the borders between HD and non-Hodgkin's lymphomas unclear. The clinical relevance of nodular lymphocyte predominance HD (LP-HD), the distinction between T-cell rich B-cell lymphoma and diffuse LP-HD, and the relationships between HD and anaplastic large cell lymphoma are reviewed and discussed.