Despite the increasing number of publications concerning 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) for post-treatment evaluation of lymphoma and the increasing availability of this novel diagnostic modality, its exact role in response assessment after therapy is still unknown. The aim of this study was to systematically review the literature regarding the diagnostic performance of dedicated FDG-PET in evaluation of first-line therapy of Hodgkin's disease and (aggressive) non-Hodgkin's lymphoma, and to calculate summary estimates of its sensitivity and specificity. The databases of PubMed and Embase were searched for relevant studies up to January 2004. Two reviewers independently assessed the methodological quality of each study. As a valid reference test, histology or follow-up of at least 12 months were accepted. A meta-analysis of the reported sensitivity and specificity of each study was performed. Fifteen studies, involving 705 patients, met the inclusion criteria. The studies had several design deficiencies. The majority of studies did not describe whether the reference test was interpreted without knowledge of the FDG-PET findings. In all studies, there was a description of the spectrum of patients included, i.e. all patients for post-treatment evaluation or only patients with substantial residual masses post-treatment. Pooled sensitivity and specificity for detection of residual disease in Hodgkin's lymphoma were 84% (95% CI 71-9192%) and 90% (95% CI 84-9394%), respectively. For non-Hodgkin's lymphoma, pooled sensitivity and specificity were 72% (95% CI 61-82%), and 100% (95% CI 97-100%), respectively. FDG-PET showed reasonable sensitivity and high specificity for evaluation of first-line therapy in Hodgkin's and in non-Hodgkin's lymphoma. Standardization of procedures is required before implementation in clinical practice.