This study aimed to evaluate the prognostic value of 2-[18F]fluoro-2-deoxy-D-glucose (18F-FDG) uptake determined by positron emission tomography (PET) in patients with non-small cell lung cancer (NSCLC) in relation to disease stage and/or tumor histology. A retrospective review of 144 patients with newly diagnosed lung cancer undergoing PET imaging was performed. Differences in survival were compared by univariate and multivariate analyses. Univariate analysis identified three prognostic factors: stage, lesion size and the standardized 18F-FDG uptake value. The latter was a better prognostic predictor in lung cancer patients with early-stage disease than in those at advanced stages. Multivariate analysis revealed that the most important prognostic factors were tumor-node-metastasis (TNM) stage and the standardized 18F-FDG uptake value. Patients with standardized uptake values (SUVs) >8 had a 2.5 times higher mortality rate than those with values ≤8. A one-unit increase in SUV corresponded with a 7% increase in the hazard of death. SUVs provided stronger prognostic stratification in patients with adenocarcinoma than in those with squamous cell carcinoma (SCC). Furthermore, the best choice of prognostic predictor differed between the two types of lung cancer: the SUV was best for SCC, while TNM stage was most significant for adenocarcinoma. In conclusion, 18F-FDG uptake in primary lung lesions is an independent prognostic predictor in patients with NSCLC, especially those with adenocarcinoma or early-stage disease. Further stratification of patients with the same TNM stage based on SUVs may allow for the modification of individual treatment strategies, resulting in improved outcome.