In the recent years, fluorine 18 fluorodeoxyglucose (18F-FDG) positron emission tomography (PET)/computed tomography (CT) has emerged as a new modality for staging non–small-cell lung cancer (NSCLC) patients. The aim of this meta-analysis was to assess the diagnostic value of 18F-FDG PET/CT in detecting metastatic lesions in NSCLC patients. Meta-analysis methods were used to pool sensitivity, specificity, positive and negative likehood ratios, diagnostic odd ratios and to construct a summary receiver-operating characteristic curve. Data from included studies were pooled to compare the diagnostic accuracy between PET/CT and PET or CT alone in nodal staging. Totally, 56 studies involving 8,699 patients met the inclusion criteria. The pooled sensitivities and specificities of 18F-FDG PET/CT were 0.72 [95% confidence interval (CI): 0.65–0.78] and 0.91 (95% CI: 0.86–0.94) in determining mediastinal nodal staging; 0.71 (95% CI: 0.60–0.80) and 0.83 (95% CI: 0.77–0.88) in intrathoracic staging; 0.78 (95% CI: 0.64–0.87) and 0.90 (95% CI: 0.84–0.94) in intrathoracic staging on a per-node basis. For detecting extrathoracic metastases, the pooled sensitivities and specificities of 18F-FDG PET/CT were 0.77 (95% CI: 0.47–0.93) and 0.95 (95% CI: 0.92–0.97) for all extrathoracic metastases; 0.91 (95% CI: 0.80–0.97) and 0.98 (95% CI: 0.94–0.99) for bone metastases. 18F-FDG PET/CT is beneficial in detecting lymph node metastases and extrathoracic metastases although PET/CT showed low sensitivity in detecting brain metastases. 18F-FDG PET/CT confers significantly higher sensitivity and specificity than contrast-enhanced CT (both p < 0.01) and higher sensitivity than 18F-FDG PET in staging NSCLC (p < 0.05).