Rationale: Elevation in Epstein-Barr virus (EBV) circulating DNA has been proposed as a marker for development of post transplant lymphoproliferative disease (PTLD), but there are few published data in lung transplant recipients. Objectives: To determine if elevated EBV DNA levels, in combination with other risk factors, were predictive of PTLD. Methods: We conducted a retrospective, single-center study examining all lung transplant recipients (n = 296) and EBV DNA levels (n = 612) using real-time TaqMan PCR. There were 13 cases of PTLD overall, of which 5 occurred in the era of EBV DNA monitoring. Measurements and Main Results: EBV DNA levels were distributed differently among seropositive and seronegative patients, with the latter having higher values (p<0.0001). Among the cohort of pre-transplantation seropositive patients, there was 1 PTLD diagnosis. The EBV DNA level in this patient was elevated at the time of PTLD diagnosis (sensitivity=100%, specificity=100% for PTLD). Among the cohort of pre-transplantation seronegative patients, there were 4 PTLD diagnoses. In all 4 patients, the EBV DNA level was detectable (sensitivity=100%, specificity=24%), but in only 2 was it elevated (sensitivity=50%, specificity=22%). HLA-A3 expression in the recipient and/or donor conferred additional risk for PTLD among the seronegative patients (p = 0.026 to 0.003). No other PTLD risk factor was found. Conclusions: EBV DNA levels are a useful but imperfect predictor of PTLD in lung transplant patients. Pre-transplant EBV status affected the results of the assay and should be considered when interpreting test results. HLA A3 was strongly linked to PTLD and may be a novel marker of PTLD risk.