The prognostic value of whole-body positron emission tomography/computed tomography(PET/CT) with 18F-fluoro-2-deoxy-D-glucose (FDG) shortly after the onset of inductionchemotherapy or mid treatment could help to predict long-term clinical outcomesin patients with Hodgkin’s or Non-Hodgkin’s lymphoma. However, FDG is nota tumor-specific substance, and it may accumulate to the point of being detected in avariety of benign conditions or at physiologic anatomical sites, which may give rise tofalse-positive interpretation. In an attempt to standardize the reporting criteria for interimPET/CT, the First International Workshop on Interim PET in Lymphoma suggestedvisual response criteria with the Deauville five-point scale, and the standardizeduptake value (SUV) has been investigated in comparison with this visual system. Aquantitative approach using the measurement of maximal SUV (SUVmax) or the reductionrate of SUVmax (ΔSUVmax) might be more appropriate in early-responsePET/CT for reducing false-positive rates or for decreasing interobserver variability ininterpretation. In this review, the predictive efficacy of PET/CT is discussed for thetreatment of aggressive lymphoma, especially in terms of an interim PET/CT-basedprognostic model.