The introduction of positron emission tomography using [F-18]fluorodeoxyglucose (FDG-PET) has had a substantial impact on the management of patients with lymphoma. Increasing numbers of patients are having an FDG-PET study as part of their initial staging, despite FDG-PET cannot be considered yet a standard procedure for staging in many types of lymphoma. FDG-PET has demonstrated its superiority over conventional imaging to identify nodal and extra-nodal sites of disease and provides complementary information to that obtained with bone marrow biopsy. This can result in disparities in the staging and prognostication of patients based on the procedures used to assess the extension of the disease. The difficulty lies in how to use the information provided by FDG-PET to communicate effectively when using staging classifications and prognostic indices that were designed following conventional imaging.