Abstract
We experienced a case of adult onset Still's disease in a 31-year-old man with a chief complaint of severe sore throat and fever. As we diagnosed him with an infectious disease at first, we gave antibiotics, but he did not recover. So, we suspected adult onset Still's disease after investigation, and the subsequent steroid therapy was effective. Adult onset Still's disease is a characterized rheumatic disorder of unknown origin, which affects multiple organs. We consider that severe sore throat is an important early symptom of adult onset Still's disease.