We evaluated the accuracy of staging in 159 patients with head and neck squamous cell carcinoma (HNSCC) scanned by FDG-PET and 116 patients with the same cancer scanned by FDG-PET/computed tomography (CT). The accuracy was measured by comparing the FDG-PET/FDG-PET/CT findings at the primary tumor site, cervical node sites and distant metastatic sites with the clinical diagnosis. Especially, accuracy at cervical sites was evaluated from the screening point of view. Both examinations yielded an accuracy rate of more than 80% for each site, and a negative predictive value of more than 90% for the cervical sites. For the cervical sites, the positive predictive value (PPV) of FDG-PET was 78% and of FDG-PET/CT was 82%. When one cervical lymph node metastasis was detected by FDG-PET, the PPV was 63%, which appears to be comparatively low. Both examinations showed high accuracy for staging of HNSCC. In the near future, excellent screening examination might become possible with the spread of FDG-PET/CT. However, both examinations do not yield the direct image of the carcinoma itself, but only the status of glucose metabolism in the carcinoma. Care must always be exercised in the interpretation, as there are not a few false negative and false positive cases.