Cytomegalovirus (CM V) infection has been a recognized complication of transfusions for nearly three decades.' More recently, it has been shown that transfusion-related CMV infections present considerable problems for the immunocompromised patient. 23 The potential morbidity and mortality due to transfusion-related CMV infections in this group of patients are very high. Policies and procedures to prevent the unintentional transmission of this virus are critical. Current strategies consist of screening blood components, leukocyte reduction of blood components, hyperimmune gamma globulin prophylaxis, and viral inactivation. The numbers of patients with temporary or permanent states of immunodeficiency who require CMV-negative blood components are increasing, and this has led to shortages in the supply. CMV-seronegative donors are a minority in the donor Physicians are encouraged to document the reasons for whatever procedure or test they use (whether or not in conformance with this guideline). Physicians should also take care to consider other medical and scientific advances that are available after the date of adoption of this guideline.This practice guideline was developed exclusively for the purposes set forth above and not for use in connection with matters involving reimbursement, credentialing, or utilization review.