An 84-year-old female patient with known Sjögren syndrome underwent 18F-FDG PET/CT to detect recurrence of uterine cervix cancer. Sjögren syndrome is autoimmune disease that typically produces symptoms of dry mouth and eyes. We report a case of physiologic 18F-FDG uptake on facial muscles by chewing-like habitual movement, which was confused with salivary retention at first. The physiologic FDG uptake in oral cavity and facial muscles has to be reviewed carefully not to be confused with abnormal uptake.