BACKGROUND: DNA of human cytomegalovirus (CMV) is frequently detected in plasma of donors with primary CMV infection. It is unknown, however, whether leukoreduced blood products from these donors contain sufficient amounts of infectious virus to cause transfusion-transmitted CMV infections (TT-CMV). STUDY DESIGN AND METHODS: During a 14-year period, CMV DNA–positive donations were identified as part of several previously published studies. Additionally, further donors with seroconversion were tested for CMV DNA. The serostatus of patients who had received a CMV DNA–positive blood product was determined out of pretransfusion samples. Later samples were examined for development of CMV antibodies. Patients with a follow-up of less than 140 days were also tested for CMV DNA. RESULTS: A total of 221 blood products from CMV DNA–positive donations were transfused to 219 recipients. Pretransfusion samples were available for 179 patients, of whom 62 (34.6%) were seronegative. For 39 seronegative recipients of 40 blood products follow-up samples drawn at least 30 days after transfusion were available. The median duration of follow-up was 287 days (range, 38-3784 days). Thirty-six patients were still CMV seronegative in their last sample. Three patients were CMV seropositive due to passive antibody transfer by plasma rich products from seropositive donors, but CMV DNA negative in all tested samples. CONCLUSION: TT-CMV was excluded in all recipients of 40 blood products from CMV DNA–positive donations. This corresponds to a 95% interval of confidence for the risk of TT-CMV of less than 7.4%. Because no patient belonged to a typical at-risk population, the results are only valid for immunocompetent subjects.