Esophageal cancer is a malignant tumor with one of the worst prognosis. Positron emission tomography (PET) reveals the degree of metabolic activity of tumor cells. We hypothesized that a high maximum standardized uptake value (SUVmax) on PET would predict a poor clinical outcome.From November 2004 to August 2011, we reviewed 88 patients with esophageal squamous cell carcinoma who underwent preoperative PET followed by surgery. SUVmax values of primary sites were measured. The patients were divided into two groups with median SUVmax as a cutoff value and outcomes were compared.The median SUVmax was 6.35. Cervical and upper thoracic cancer, large tumor size, stage ≥ T2, and lymph node metastasis were significantly associated with the high SUVmax group. Cervical and upper thoracic cancer (p = 0.038), SUVmax (p = 0.038), number of lymph nodes dissected (p = 0.009), stage ≥ T2 (p = 0.003), lymph node metastasis (p < 0.001), and incomplete resection (p = 0.031) were significant predictors for the disease-free survival. A high SUVmax ( ≥ 6.35, p = 0.023) and stage ≥ T2 (p = 0.025) were significantly associated with overall survival by multivariate analysis.High preoperative SUVmax on PET predicts advanced T stage and worse prognosis. SUVmax on PET may provide useful information combined with current stage for determining optimal treatment in esophageal cancer.