A total of 186 specimens of Hodgkin's disease of various histologic types (127 nodular sclerosis, 39 mixed cellularity, 14 lymphocyte predominance, 3 lymphocyte depleted, and 3 unclassified) were evaluated for the presence of latent membrane protein (LMP) and Epstein-Barr virus nuclear antigen-2, two Epstein-Barr virus encoded gene products that appear to play important roles in cell transformation and oncogenesis. Immunoreactivity for LMP was observed in Reed-Sternberg cells and variants of 27/39 (69%) cases of mixed cellularity type, 18/127 (14%) of nodular sclerosis type, 2/3 cases of lymphocyte depleted type, and 1/3 cases of unclassified type. All cases of lymphocyte predominance Hodgkin's disease were nonreactive for LMP. In cases that were reactive for LMP, staining was restricted to Reed-Sternberg cells and variants. Other cells within the proliferation, e.g., lymphocytes, histiocytes, eosinophils, fibroblasts, etc., were nonreactive. The pattern of immunoreactivity for LMP was characterized by strong diffuse cytoplasmic staining, occasionally with membrane accentuation and/or paranuclear staining. Reactivity for LMP was demonstrated in cryostat sections and was also well preserved in paraffin sections of B5- or formalin-fixed tissues. Five of six specimens of Hodgkin's disease (4 mixed cellularity and 2 nodular sclerosis type) that occurred in HIV-positive patients exhibited immunoreactivity for LMP in Reed-Sternberg cells and variants. Cryostat section studies for Epstein-Barr virus nuclear antigen-2 using monoclonal antibody PE-2 failed to reveal staining for 43 cases (26 nodular sclerosis, 12 mixed cellularity, and 5 lymphocyte predominance) after a 2-h incubation with primary antibody.(ABSTRACT TRUNCATED AT 250 WORDS)