PURPOSE: (18)F-fluorodeoxyglucose positron emission tomography (FDG-PET) is currently not used on a routine basis for imaging of neuroendocrine (NE) tumors. The aim of this study was to investigate the prognostic value of FDG-PET in patients with NE tumors. EXPERIMENTAL DESIGN: Ninety-eight prospectively enrolled patients with NE tumors underwent FDG-PET imaging. FDG uptake was quantified by maximal standardized uptake value (SUVmax). The prognostic value of FDG uptake, proliferation index, chromogranin A, and liver metastases were assessed. RESULTS: During the 1-year follow-up, 14 patients died. The diagnostic sensitivity of FDG-PET was 58% (n = 57) and a positive FDG-PET result was associated with a significantly higher risk of death with a hazard ratio (HR) of 10.3 [95% confidence interval (CI), 1.3-78.9]. Thirteen of the 57 (23%) FDG-PET-positive patients died compared with 1 of 41 (2%) FDG-PET-negative patients. By univariate analysis, a SUVmax of >9 and a high Ki67 index were significant predictors of overall survival with a HR of 8.8 (95% CI, 2.7-28.7) and a HR of 2.6 (95% CI, 1.3-5.1), respectively. In a multivariate analysis including a SUVmax of >3, Ki67, and chromogranin A, SUVmax of >3 was the only predictor of progression-free survival (HR, 8.4; P < 0.001). CONCLUSIONS: This study shows a strong prognostic value of FDG-PET for NE tumors, which exceeds the prognostic value of traditional markers such as Ki67, chromogranin A, and liver metastases. FDG-PET may obtain an important role for NE tumors.