Background: The stage of esophageal cancer is currently determined by the anatomic TNM classification system as opposed to information about tumor biology. Methods: A retrospective review was made of a prospective electronic database. Patients had esophageal cancer, dedicated positron emission tomography (PET) using F-18-fluorodeoxyglucose (FDG-PET) and maximum standardized uptake value (maxSUV) measured. Biopsies were obtained from suspicious nodal and systemic locations, and when indicated, resection with complete lymphadenectomy was performed. Results: There were 89 patients (53 men). The median maxSUV for patients with high grade dysplasia, stage I, IIa, IIb, III, and IVa esophageal cancer was 1.7, 2.9, 8.9, 7.7, 9.5, and 12, respectively. Multivariate analysis showed patients with a high maxSUV were more likely to have poorly differentiated tumors (risk ratio 1.89, p = 0.032) and advanced stage (risk ratio 2.6, p < 0.001). The maxSUV correlated better (r 2 = 0.85) than the current TNM staging system for survival (r 2 = 0.68). Receiving operator characteristics curve demonstrated a maxSUV of 6.6 to be the optimal cut-off point. The 4-year survival of patients with a maxSUV of 6.6 or less was 89%, whereas it was only 31% for those patients with values greater than 6.6 (p < 0.001). Conclusions: The maxSUV of an esophageal cancer on dedicated FDG-PET scan is an independent predictor of stage, tumor characteristics, and survival. It predicts survival better than the current TNM staging system. This information may help guide treatment strategies. © 2006 The Society of Thoracic Surgeons.