A 65-year-old man was diagnosed with hepatocellular carcinoma 4 years ago, for which he underwent interventional therapy and radiofrequency ablation after the right lobe partial hepatectomy. He was doing well, and an FDG PET/CT scan performed 1 year earlier did not reveal any hypermetabolic lesions. However, on recent examination, a soft tissue mass inside the oral cavity was found. 18F-FDG PET/CT imaging was performed to evaluate the possible metastasis. The images showed that the oral lesion was hypermetabolic. The pathology after biopsy confirmed oral metastasis from hepatocellular carcinoma.