We used the polymerase chain reaction, in situ hybridization, and immunohistochemical stains against latent membrane protein, CD23, and Epstein-Barr viral nuclear antigens 1 and 2 to identify Epstein-Barr virus (EBV) in fixed and unfixed (cryopreserved) AIDS-related lymphoma (ARL) specimens. The study included 17 cases of large-cell (immunoblastic) lymphoma, 11 cases of small non-cleaved cell lymphoma, and two cases of Hodgkin's disease. The EBV DNA was more frequently detected by polymerase chain reaction in cryopreserved specimens (94%) than in fixed specimens (17%). Significantly, the immunohistochemical and in situ hybridization studies detected evidence of EBV in only a small (< 10%) subset of the cells in 27 of 30 ARL specimens. We conclude that tissue fixation reduced the ability to detect EBV in ARL by polymerase chain reaction and that EBV was detectable in only a minority of cells in most ARL tissues.