The authors studied typical Hodgkin's disease along with the nodular, lymphocyte predominance subtype by both the polymerase chain reaction (PCR) and in situ hybridization for evidence of the Epstein-Barr virus (EBV). By PCR, EBV DNA was detected in 12/23 cases of typical Hodgkin's disease and 2/13 cases of the nodular, lymphocyte predominance subtype. EBV RNA was detected by in situ hybridization studies within Reed-Sternberg cells and variants in 11/23 cases of typical Hodgkin's disease and 0/13 cases of nodular, lymphocyte predominance Hodgkin's disease. Other cells positive for EBV, identified as both B and T cells in double-labeling immunohistochemical/in situ hybridization studies, were found in 20/23 cases of typical Hodgkin's disease, 9/13 cases of nodular, lymphocyte predominance Hodgkin's disease, 4/6 cases of progressive transformation of germinal centers, and 7/10 normal lymphoid tissues. It is concluded that EBV is significantly associated with Reed-Sternberg cells in approximately one-half cases of typical Hodgkin's disease but not in the nodular, lymphocyte predominance subtype. EBV-infected B and T cells are also present in a majority of cases of Hodgkin's disease as well as in reactive conditions.