At least one-quarter of the non-Hodgkin's lymphomas arise primarily at extranodal sites. The rising incidence of non-Hodgkin's lymphomas, observed over recent decades, have mainly affected the primary extranodal entities. Survival rates vary among the specific sites of primary extranodal lymphomas. This is due partly to differences in natural history, related mainly to the histological type but also to differences in management strategy which are related to organ-specific problems. Few controlled studies facilitate therapeutic decisions in this setting. This chapter represents a general overview of the available data.