A 74-year-old woman presented to the emergency department with a 3-day history of headache and tongue swelling with associated pain, as well as several hours of blindness in the right eye. On physical examination, the tongue was discolored and ulcerated (Panel A), and the right temporal artery was thickened. Laboratory studies revealed an erythrocyte sedimentation rate of 42 mm per hour (reference value, <42) and a C-reactive protein level of 169 mg per liter (reference range, 0 to 5). Biopsy specimens of the temporal arteries showed giant cells and an inflammatory infiltrate throughout the vessel wall, findings that confirmed a diagnosis of giant-cell arteritis. Lingual infarction is a rare complication of giant-cell arteritis, and this condition should be considered in the differential diagnosis of tongue necrosis. The patient was admitted to the hospital and received tocilizumab and high-dose glucocorticoids. Her vision returned, and she was discharged, with a plan to continue a prolonged tapering of the glucocorticoid dose. At a follow-up visit 2 months after presentation, the tongue necrosis had abated (Panel B).