Purpose The aim of this study was to evaluate the role of 18 Ffluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) in the staging of Hodgkin’s and aggressive non-Hodgkin’s lymphoma (HL and NHL), comparing it with conventional diagnostic methods, i.e. contrast-enhanced CT and bone marrow biopsy. Materials and methods Sixty-five consecutive patients (30 HL and 35 NHL) who underwent conventional disease staging and FDG-PET/CT were included. Concordance between conventional methods and PET was established when both procedures identified the same disease stage. Discordant findings were investigated further by using other diagnostic techniques (ultrasonography or magnetic resonance imaging) and/or clinical follow-up. Results PET correctly staged 93.8% of enrolled patients (61/65), whereas conventional techniques correctly staged 89.2% (58/65; p =NS, gC 2 test). There was complete concordance in 54/65 patients (83.1%); among the remaining 11 cases, PET upstaged eight patients (seven true positive and one false positive), and downstaged three (all false negative). In 5/65 patients, chemotherapy treatment was modified on the basis of PET findings. Conclusions Our data confirm the high accuracy of FDG-PET/CT in staging HL and NHL. FDG-PET/CT should therefore be used routinely in the initial evaluation of both patient subgroups.