Paraffin sections from 21 cases of Hodgkin's disease (HD), 28 cases of non-Hodgkin's lymphomas (NHL) and 34 cases of non-specific reactive lymphadenitides occurring in childhood were examined for the presence of the Epstein-Barr Virus (EBV)-encoded Latent Membrane Protein (LMP) using a double layer immunohistochemical method. LMP was detected in 12/21 (57%) cases of HD but not in NHL or reactive lymph nodes. LMP reactivity was restricted to Reed-Sternberg and Hodgkin's (HRS) cells in 4 of 9 (45%) cases of nodular sclerosis (NS), 6 of 9 (66%) cases of mixed cellularity (MC) and 2 of 2 (100%) cases of lymphocyte depletion (LD) while it was undetectable in the single case of lymphocyte predominance (LD) subtype. These results provide further evidence for an association between EBV and Hodgkin's disease, and they show that LMP expression occurs more frequently in the clinically more aggressive subtypes of HD. Furthermore, in view of the in vitro transforming potential of the LMP protein, the exclusive immunolocalization of LMP in HRS cells, suggests that EBV may be involved in the pathogenesis of a proportion of cases of HD.