The purpose of the present study was to assess the contribution of simultaneous functional/anatomical imaging using integrated 18F-fluorodeoxyglucose-positron emission tomography/computed tomography (FDG-PET/CT), compared with PET alone for the evaluation of initial lymph node staging in esophageal cancer. We studied 167 consecutive patients with thoracic esophageal squamous cell carcinoma (SCC) who had radical esophagectomy performed between January 1999 and April 2007. For individual nodal group evaluation, PET/CT showed 46.0% sensitivity (p<0.05 vs. PET), 99.4% specificity, 95.1% accuracy (p<0.05 vs. PET), 87.0% positive and 95.5% negative predictive values. PET showed 32.9% sensitivity, 98.9% specificity, 93.1% accuracy, 74.7% positive predictive value and 93.9% negative predictive value. Thus, the sensitivity and accuracy of PET/CT were significantly higher than those of PET. Comparisons between CT, PET and PET/CT in detecting lymph node metastasis by each region showed that PET/CT had a higher sensitivity in lower thoracic regions than PET and CT (p<0.05 vs. CT and PET). Lymph node staging (N0 vs. N1) was not significantly different, but staging per lymph nodal group was significantly better with PET/CT. Integrated PET/CT imaging with co-registration of anatomic and functional imaging data is useful in the initial lymph node staging of patients with operable esophageal cancer compared with PET alone.