Monitoring of the Epstein-Barr virus–DNA load is frequently used to identify patients at risk for post-transplant lymphoproliferative disease (PTLD). Epstein-Barr virus DNA can be measured in the plasma and whole blood serum compartments.We compared levels of Epstein-Barr virus DNA in whole blood and plasma using a real-time TaqMan polymerase chain reaction assay in 100 consecutive paired whole blood and plasma samples from 25 lung and heart-lung transplant recipients with detectable whole blood Epstein-Barr virus–DNA load (>2,000 copies/ml).A correlation (r 2 ) of 0.58 (p < 0.001) was observed between both measurements, whereas of the positive whole blood samples (>2,000 copies/ml), only 17 samples (18%) were also positive in plasma.These results indicate that by virtue of its sensitivity, whole blood rather than plasma may be the preferable specimen for the detection of Epstein-Barr virus DNA in lung transplant recipients.