Epstein-Barr virus (EBV) has been demonstrated in association with Hodgkin's disease (HD) in approximately 40 to 50% of cases in series from North America, Europe, and Japan. However, few data are available concerning this association in developing countries. Recent studies, including mostly a pediatric population from Peru and a pediatric population from Honduras, showed a higher percentage of EBV positivity compared with those in developed countries. To determine the prevalence of EBV in Hodgkin's disease in a Mexican adult population, we analyzed 50 formalin-fixed, paraffin-embedded cases of HD by a three-step technique using a monoclonal antibody to the latent membrane protein of EBV. All the cases were confirmed immunophenotypically as HD (CD15+ and/or CD30+, CD45-). Reed-Sternberg cells and variants were positive for LMP in 35 cases (70%). The staining was found both on the cell surface and/or within the cytoplasm with enhancement of the Golgi area. EBV latent membrane protein was found in 1/1 case (100%) of diffuse lymphocyte-predominant HD, 10/20 cases (50%) of nodular-sclerosis, 18/22 cases of mixed-cellularity (81%), and 6/7 (86%) cases of lymphocyte-depleted HD. Our results show a high prevalence of EBV in HD in this Mexican adult population. All histologic subtypes of HD in the population analyzed appear to be strongly associated with EBV, in contrast to the strong association of mixed cellularity HD in developed countries. Patient age and gender were not predictive of the presence of EBV.