Joint pain is the most common symptom in rheumatology, and more than 80% of patients in outpatient clinics may be seen in rheumatology for joint pain; however, joint pain is also the most complex. Almost all rheumatologic diseases can present with joint pain symptoms, either arthritis with inflammation and redness, or simple, joint pain without inflammation or redness. If you have joint pain symptoms, then you may have osteoarthritis, gout, or systemic lupus erythematosus, ankylosing spondylitis, or rheumatic fever, reactive arthritis, or psoriatic arthritis, dry syndrome, or vasculitis, scleroderma …… There are too many, too many possibilities to say and explain. Many people, especially children and adolescents (5-15 years old), may have knee pain after a cold or sore throat, and somehow this joint pain starts again after that joint pain, or several joints pain at the same time. Then, this may be caused by rheumatic fever. When it comes to rheumatic fever, many people may not be impressed, but when it comes to rheumatic heart disease, you may be familiar with it. Rheumatic fever was very common in China before the 1990s, and the cause was group A beta-hemolytic streptococcal infection. Nowadays, due to the application of penicillin, this disease has been greatly reduced, however, you can still encounter many such patients in outpatient clinics. Joint pain is the most common symptom of rheumatic fever, mostly pain and inflammation of large joints, such as knee, ankle, elbow, wrist and shoulder joints, with local manifestations of redness, swelling, heat and pain (pain and pressure), often recurrent and wandering, with pain here and there, and more pain on rainy, cold and humid days, sometimes unable to walk. Therefore, when the above symptoms appear, you should be especially careful if it is rheumatic fever. However, rheumatic fever is not only about joint pain, it may involve the heart and lead to heart disease, such as valve lesions, pericarditis, tachycardia, and in severe cases, palpitations, chest tightness, and shortness of breath. Fever, rash, subcutaneous nodules, and chorea may also occur. Therefore, if you have many of the above symptoms, it is more important to be alert.