OBJECTIVE To determine whether the amount of fluorine-18 fluorodeoxyglucose (FDG) uptake in the primary lung cancer on positron emission tomography (PET) imaging at the time of presentation has prognostic significance in patients with advanced-stage non-small-cell lung cancer (NSCLC). METHODS A retrospective review identified 214 patients with advanced-stage NSCLC (stage IIIA, IIIB, and IV) who underwent FDG PET study at the time of diagnosis. Extensive clinical data, including tumor histologic cell type, pathologic stage at presentation, and treatment, were recorded. The maximum standardized uptake value (SUV(max)) in the primary tumor on FDG PET on survival was examined using Cox proportional hazards regression. RESULTS One hundred fifty-eight (74%) of the 214 patients died and 56 patients were reported alive at 27 months (range, 3 to 140 months) after the diagnosis of NSCLC. Using the median SUV(max) of 11.1, the patient population was subdivided. The median survival of the 106 patients with the primary tumor having an SUV(max) less than 11.1 was 16 months (95% CI, 12 to 21 months), whereas the median survival of the 108 patients with the primary tumor having an SUV(max) > or = 11.1 was 12 months (95% CI, 10 to 15 months). Univariate and multivariate analysis did not provide evidence that survival for patient subgroups defined by the median SUV(max) were significantly different (univariate P = .11; multivariate P = .45). CONCLUSIONS FDG uptake of the primary lesions in patients with a new diagnosis of advanced-stage NSCLC does not have a significant relationship with survival.