CMV-specific immunity was assessed in a longitudinal cohort of 39 lung transplant recipients (LTR) who were followed prospectively from the time of transplant using a novel assay. At the time of surveillance bronchoscopy, CMV-specific CD8(+) T-cell responses were assessed in the peripheral blood, using the QuantiFERON-CMV assay, which measures IFN-gamma-secreting T cells following stimulation with CMV peptides. In total, 297 samples were collected from 39 LTR (CMV D+/R-, n = 8; D+/R+, n = 18; D-/R+, n = 6; D-/R-, n = 7). CMV-specific T-cell immunity was not detected in any of the CMV D-/R- LTR. In CMV seropositive LTR levels of CMV immunity were lowest early posttransplant and increased thereafter. While levels of CMV-specific immunity varied between LTR, measurements at any one time point did not predict episodes of CMV reactivation. In CMV mismatched (D+/R-) LTR, primary CMV immunity was not observed during the period of antiviral prophylaxis, but typically developed during episodes of CMV reactivation. Measuring CMV-specific CD8(+) T-cell function with the QuantiFERON-CMV assay provides insights into the interrelationship between CMV immunity and CMV reactivation in individual LTR. A better understanding of these dynamics may allow the opportunity to individualize antiviral prophylaxis in the future.