Intercellular adhesion molecule-3 (ICAM-3), the third receptor for lymphocyte function-associated antigen molecule-1 and a new member of the immunoglobulin superfamily has been recently characterized using specific monoclonal antibodies. In the present study, we show immunocytochemically that ICAM-3 is present on T and B cells in the mantle zones and on a subpopulation of follicular center cells in reactive lymph nodes and only occasionally in endothelium. In 52 cases of Hodgkin's disease, ICAM-3, although present on the majority of the reactive lymphoid cells, was absent from the Reed-Sternberg cells and their variants. However, in 28 cases (54%), there was prominent endothelial staining in small vessels. Similar findings were noted in 16 out of 49 cases (33%) of non-Hodgkin's lymphomas. This finding suggests that analogous to ICAM-1 and ICAM-2, ICAM-3 expression can be induced on endothelial cells in lymphoid neoplasms, probably by an as yet unidentified cytokine-mediated mechanism.