A systematic survey of human cytomegalovirus (CMV) was performed in 29 allogeneic bone marrow transplant (BMT) recipients. At day 100 a lip biopsy was performed and histological grading according to Sale's score was compared with the immunohistochemical detection of the immediate early protein IE2 of HCMV. In 10 patients without chronic graft-versus-host disease (GVHD), 3 had lip biopsy grade 1, 7 had grade 0 Sale's score and in 19 patients with chronic GVHD, 11 had grade 2, 1 had grade 1 and 7 had grade 0. On the same lip biopsies, we found IE2 protein in 8 of the 19 patients with chronic GVHD. None of the lip biopsies from patients without chronic GVHD expressed the protein, suggesting that HCMV expression is strongly associated with chronic GVHD and Sale's grade 2. To conclude, in our group of patients with a risk for HCMV infection, detection of the protein IE2 was a good predictive criterion of chronic GVHD with a sensitivity of 61% and a specificity of 100%.