The accurate staging of Hodgkin's disease (HD) and non- Hodgkin's lymphoma (NHL) is an important aspect of treatment. In this study, the authors undertook to prospectively evaluate the clinical value of 2-(fluorine-18)fluoro-2-deoxy-D- glucose position emission tomography (FDG-PET) for the staging of malignant lymphoma as compared with computed tomography and 67Ga scan. Thirty consecutive cases with biopsy-proven lymphoma (4 HD, 26 NHL) were examined by FDG-PET for the initial staging and the restaging work-up between September 2000 and April 2001. The FDG-PET and conventional study, including a CT of the neck, chest, abdomen, and of the pelvis, a bone scan, a 67Ga scan, and a bone marrow study were undertaken to investigate nodal/extranodal manifestations and bone marrow infiltration. In terms of the detection of nodal lymphoma manifestation, the sensitivities and specificities of the PET, CT, and 67Ga scan were determined to be 93.3%, 98.9%, and 25.8%, and 100%, 99.1%, and 99.8%, respectively. In terms of the detection of extranodal lymphoma manifestation, the sensitivities and specificities of the PET, CT, and 67Ga scan were 87.5%, 87.5%, and 37.5%, and 100%, 100%, and 100%, respectively. The FDG-PET proved to be very accurate for the staging of malignant lymphoma and superior to Ga-67 scan. Although the results of PET and CT were substantially comparable, both imaging studies were found to complement each other in some cases with respect to the evaluation of lymphomatous involvement.