Mononucleosis, i.e. infectious mononucleosis, is an acute infectious disease caused by EBV, which mainly affects children and adolescents, with anti-EBV antibodies appearing in the body after infection, and is a self-limiting disease. 1. The main transmission route of infectious mononucleosis is oral-oral transmission. Clinical features include fever, pharyngitis, enlarged liver and spleen lymph nodes, hepatosplenomegaly, skin rash, etc. There is a significant increase of lymphocytes in peripheral blood and the appearance of abnormal lymphocytes, and the serum heterophilic agglutination test is positive. 2. Diagnosis of infectious mononucleosis can be made on the basis of clinical manifestations and relevant examinations (e.g., marked increase in peripheral blood lymphocytes, abnormal lymphocytes, positive serum heterophilic agglutination test, and EBV-specific antibody test). 3. Infectious mononucleosis is a self-limiting disease with a good prognosis. Treatment includes the application of gammaglobulin and antiviral drugs, such as acyclovir, ganciclovir, and alpha-interferon, etc., which should be used under the guidance of a physician. Patients with infectious mononucleosis should seek prompt medical attention and follow doctor’s instructions.