Hemolysin o is a metabolite with hemolytic activity produced by group a hemolytic streptococci, and its corresponding antibody is called anti-streptococcal hemolysin o. Clinically, if anti-streptococcal hemolysin o is found to be positive, it indicates that the patient has had a recent group a hemolytic streptococcal infection, but it does not indicate a presenting infection. Increased anti0 can be seen in rheumatic fever, rheumatic myocarditis, active rheumatic fever, acute glomerulonephritis, acute upper respiratory tract infections, and infections of the skin and soft tissues. Clinically, if high anti-streptococcal hemolysin o is found in combination with increased acute chronological reactants such as hematocrit and CRP, it should belong to the acute phase and should be promptly seen. However, the role of antio in this also requires targeted treatment according to the different diseases.