A 47-year-old woman received an allogeneic bone marrow infusion because of chronic myeloid leukemia. Two months after the transplant she developed an interstitial pneumonia: bronchoalveolar lavage yielded cytomegalic cells with intranuclear bodies, and cytomegalovirus DNA was detected by in situ hybridization techniques. Ganciclovir and standard high-dose immunoglobulins were administered to the patient with resolution of the pneumonia. No relapse of pneumonia was observed after a 4-month follow-up. It seems that the favorable outcome of the potentially fatal pneumonia observed in this patient might be related to early diagnosis, and prompt administration of ganciclovir and standard high-dose immunoglobulins.